What are the different types of skin pores. How do pores contribute to skin health. What causes blocked pores and acne. How can you maintain healthy pores. What treatments are available for enlarged pores.

The Importance of Skin Pores in Maintaining Healthy Skin

Skin pores play a crucial role in maintaining the health and function of our skin. Despite the common desire for “poreless” skin promoted by many skincare advertisements, these tiny openings serve essential purposes. Let’s delve into the world of pores to understand their significance and how they contribute to overall skin health.

What are skin pores?

Skin pores are small openings on the surface of the skin that allow oil and sweat to reach the skin’s surface from glands located beneath. These microscopic structures are present all over our body and serve as vital channels for the skin’s natural processes.

Two Types of Skin Pores: Oil and Sweat

There are two distinct types of pores found on our skin, each serving a unique purpose:

• Oil pores: Connected to sebaceous glands, these pores are found all over the body except for the palms of hands and soles of feet. They are typically larger and more noticeable, often the focus of skincare concerns.
• Sweat pores: These tiny, nearly invisible pores are connected to sweat glands and are present across the entire skin surface. When overactive, they can lead to conditions like hyperhidrosis (excessive sweating).

The Function of Healthy Pores in Skin Maintenance

Healthy pores perform essential functions that contribute to skin health and overall well-being:

Oil pores and sebum production

Oil pores allow sebum, the skin’s natural oil produced by sebaceous glands, to reach the surface. This process is vital for:

• Keeping the skin supple and moisturized
• Protecting the skin from external factors
• Maintaining overall skin health

Sweat pores and temperature regulation

Sweat pores enable the release of sweat from sudoriferous glands, which plays a crucial role in:

• Regulating body temperature through evaporative cooling
• Eliminating toxins from the body
• Maintaining skin hydration

The Link Between Blocked Pores and Acne Development

While pores are essential for skin health, they can sometimes become problematic, leading to skin issues such as acne. Understanding this connection is crucial for effective skincare.

How do blocked pores lead to acne?

Acne development is closely tied to the function of pores, sebaceous glands, and sebaceous ducts. The process typically unfolds as follows:

1. Oil and dead skin cells accumulate within the pore
2. Instead of being cleared out, these substances become trapped
3. The blockage leads to the formation of various types of acne blemishes

All acne blemishes, from blackheads to inflamed breakouts, begin with a pore blockage. This underscores the importance of maintaining clear pores in acne prevention and treatment.

Factors Influencing Pore Size and Appearance

The size and appearance of pores can vary greatly from person to person and are influenced by several factors:

• Genetics: Pore size is largely determined by genetic factors
• Age: As we age, skin loses elasticity, which can make pores appear larger
• Sun damage: Excessive sun exposure can lead to enlarged pores
• Skin type: Oily skin tends to have more noticeable pores
• Hormonal changes: Fluctuations in hormones can affect pore appearance

Maintaining Healthy Pores: Tips and Techniques

While it’s not possible (or desirable) to completely eliminate pores, there are ways to maintain their health and minimize their appearance:

How can you keep your pores clean and functioning properly?

• Cleanse regularly: Use a gentle, non-comedogenic cleanser twice daily
• Exfoliate: Incorporate chemical exfoliants like salicylic acid or glycolic acid into your routine
• Use non-comedogenic products: Choose skincare and makeup products that won’t clog pores
• Protect from sun damage: Use broad-spectrum sunscreen daily
• Stay hydrated: Proper hydration helps maintain skin elasticity
• Maintain a healthy diet: Consume foods rich in antioxidants and omega-3 fatty acids

Treatment Options for Enlarged Pores and Acne

For those struggling with enlarged pores or acne, several treatment options are available:

What professional treatments can help minimize pore appearance?

• Chemical peels: Help remove dead skin cells and unclog pores
• Microdermabrasion: Exfoliates the skin and can improve pore appearance
• Laser treatments: Can help tighten skin and reduce pore size
• Prescription medications: Topical retinoids or oral medications for severe acne

The Role of Skincare Products in Pore Health

Choosing the right skincare products is crucial for maintaining healthy pores and preventing blockages. Consider incorporating the following into your routine:

Which ingredients are beneficial for pore health?

• Salicylic acid: Helps exfoliate inside the pore
• Niacinamide: Can help regulate sebum production
• Retinoids: Promote cell turnover and can help unclog pores
• Clay masks: Can help absorb excess oil and cleanse pores

Remember that what works for one person may not work for another. It’s essential to find a skincare routine that suits your individual skin type and concerns.

Debunking Common Myths About Pores

There are many misconceptions about pores that can lead to improper skincare practices. Let’s address some common myths:

Can pores open and close?

Contrary to popular belief, pores do not open and close like doors. They may appear larger or smaller due to factors like temperature or product use, but they don’t physically open or close.

Is it possible to shrink pores permanently?

While you can’t permanently change the size of your pores, you can minimize their appearance through proper skincare and treatments. Pore size is largely determined by genetics and age.

Do all pores produce oil?

No, only oil pores connected to sebaceous glands produce oil. Sweat pores, which are connected to sweat glands, do not produce oil.

Understanding these facts about pores can help you make more informed decisions about your skincare routine and treatments.

The Impact of Lifestyle Factors on Pore Health

Your daily habits and lifestyle choices can significantly affect the health and appearance of your pores. Consider the following factors:

How does diet affect pore health?

While the link between diet and skin health is complex, some studies suggest that certain foods may influence sebum production and skin inflammation. A balanced diet rich in fruits, vegetables, and omega-3 fatty acids may contribute to overall skin health.

What role does stress play in pore-related skin issues?

Stress can trigger hormonal changes that may increase sebum production, potentially leading to clogged pores and acne. Stress management techniques like meditation or exercise may indirectly benefit your skin health.

How does sleep affect your pores?

Adequate sleep is crucial for skin regeneration and repair. Lack of sleep can lead to increased stress hormones and inflammation, potentially exacerbating skin issues.

By addressing these lifestyle factors, you may be able to improve your overall skin health and the appearance of your pores.

The Future of Pore Care: Emerging Technologies and Treatments

As our understanding of skin biology advances, new technologies and treatments for pore-related concerns are emerging:

What innovative treatments are on the horizon for pore care?

• Nanotechnology: Developing targeted treatments that can penetrate deep into pores
• Personalized skincare: Using genetic testing to create customized skincare regimens
• Advanced laser treatments: Refining existing laser technologies for more effective pore refinement
• Microbiome-based treatments: Harnessing the power of beneficial skin bacteria to maintain pore health

While these technologies are still evolving, they represent exciting possibilities for the future of pore care and overall skin health management.

Conclusion: Embracing Your Pores for Healthy Skin

Understanding the vital role that pores play in skin health is crucial for developing an effective skincare routine. Rather than trying to eliminate or shrink pores, focus on keeping them clean and functioning properly. Remember that some variation in pore size is normal and even necessary for healthy skin function.

By adopting a holistic approach to skincare that includes proper cleansing, protection from environmental damage, and a healthy lifestyle, you can maintain the health of your pores and achieve your best skin. Embrace your pores as an essential part of your skin’s ecosystem, and work with them, not against them, for optimal skin health.

What Are Pores and How Do They Contribute to Acne?

If you believe the skincare ads, everyone wants pores so tiny they can’t be seen, as well as pores that aren’t blocked or clogged. You may wonder how you can reduce the size of your pores and whether you can simply eliminate them. But pores keep your skin and body healthy—and if blocked, can contribute to acne.

PeopleImage.com / Digital Vision / Getty Images

Two Types of Skin Pores

The term pore is used to describe the small openings in the skin in which oil and sweat reach the surface from their respective glands below. You actually have two different types of pores: oil pores and sweat pores.

• Oil pores: This type of pore is connected to an oil gland. You have these over the entire surface of your entire skin, except for the skin on the palms of your hands and the soles of your feet. It’s the oil pores that capture most of our attention because they can be large enough to be seen. When people talk about having large pores or blocked pores, they are typically referring to the oil pores.
• Sweat pores: You also have sweat pores all over your entire skin. Sweat pores are really tiny. You typically can’t see these pores with the naked eye. When overactive, these pores can cause hyperhidrosis (excessive sweating).

How Healthy Pores Work

Your pores have a very important job. The hair follicle allows the oil generated by the sebaceous glands (oil glands) to reach the surface and lubricate the skin. The skin’s natural oil, called sebum, helps keep the skin supple, moisturized, and healthy. You don’t want to stop production of sebum or shrink away pores, but rather to keep them functioning normally to have healthy skin.

Sweat pores work in much the same way. These pores allow for sweat to travel from the sudoriferous glands (sweat glands) to the surface of the skin. Sweat helps you maintain your body temperature by evaporative cooling. Sweat glands come in two varieties. The eccrine glands produce most of your sweat. The apocrine glands in your armpits and groin produce a thicker and oilier type of sweat that is prone to causing body odor.

Blocked Pores and Acne Development

Acne is a disorder of the pore, sebaceous (oil) glands, and sebaceous (oil) duct. Altogether these make up the pilosebaceous unit.

Typically, your pores do a great job of sweeping out oil, dead skin cells, and other gunk that may end up there. But sometimes this process goes awry. Instead of being cleared up and out of the pore, oil and dead cells become trapped in the hair follicle.

All acne blemishes begin as a pore blockage. This includes blackheads, milia, small pimples, and large inflamed breakouts. To get acne under control, a treatment that keeps pores clear is a must.

Incidentally, sweat pores can become blocked, although an acne blemish doesn’t form. Instead heat rash or “prickly heat” develops.

A Word From Verywell

Even though they’re small, your pores are an important part of your skin. You don’t want to close your pores as that would prevent their proper functioning. There are various cosmetic treatments for enlarged pores. While pore size is largely genetic, exfoliating treatments can help minimize their appearance.

How Skin Pores Work | HowStuffWorks

Although we’re not covered head to toe in a suit of fur, our skin is abundant with hair follicles, tiny shafts through which hair can grow and reach the skin.

“Follicles” and “pores” are sometimes used interchangeably, and other times referred to as two different things. In truth, the pore is simply the opening upon the skin of the hair follicle, which extends downward through several layers of skin.

If a hair follicle were a tall chimney, the pore would be the opening at the top of the chimney. Instead of emitting smoke, the follicle emits a shaft of hair. Skin cells are constantly dying inside the follicle. Additionally, small sebaceous glands located inside the follicle (picture a cul-de-sac located off to the side of an otherwise straight road) produce oil called sebum. Sebum is a mixture of fats, proteins, cholesterol and inorganic salts. It travels up the follicle and (in a perfect world) exits through the pore. It also carries those dead skin cells found within the follicle up to the skin’s surface.

What about sweat — doesn’t that come out of the same pores? No. Sweat is produced by separate sweat glands that also heavily populate your skin. While sweat emerges from the skin from a different source, it does affect your skin’s appearance. Once that sweat reaches the surface, it dries but leaves salts behind that can block your pores.

This mix of oil and dead skin cells helps coat your skin to protect it from bacteria, viruses, wind and rain (we sort of take our skin’s protective qualities for granted). Sometimes, though, the pore is occluded (blocked) and the materials trying to get out can’t, resulting in acne.

For more information about skin cells, read Skin Cells: Fast Facts.

If you have large pores, there’s some good news — but you may have to wait a few years to receive its benefits. As we age, our skin produces less oil, leading to dryness. This dryness, coupled with environmental damage to the skin, causes skin to age and wrinkle. Large pores produce more oil, and this comes in handy later in life when your skin needs it most. So while you may be bugged by the appearance and size of your skin pores today, you’re just getting an early start — and their existence will please you down the road.

Next: Maintaining clean, open pores.

All You Need To Know About Pores: Function, Myths, Treatments

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Even though they serve a vital role, pores get a seriously bad rap. It seems like every other product’s goal is to banish them out of sight, and they can be a major source of woe for people of all ages, ethnicities, and skin types. As such, many quickly scramble to reduce pore size without first understanding why they’re there or how they work. This can lead to misinformation and therefore mistreatment of your skin.

Today we’re taking a couple steps back to discuss pore function and address some common myths. Once you’re equipped with that info, we’ll then dive into proper pore treatment so you can better keep them—and your skin—happy and healthy.

How Pores Work

Pores are actually hair follicles that house tiny hairs. They are also where the sebaceous (oil) glands and sudoriferous (sweat) glands live. “More than that, both sebum and sweat are secreted out of pores,” explains Rachael Pontillo, a holistic skincare expert and author of the book, Love Your Skin, Love Yourself. While you may associate that slick, oily feeling with only bad things—namely a shiny face—excreting oil via your pores is your body’s way of lubricating and protecting your skin. And when your body excretes sweat, that’s its way of detoxifying and cooling down.

“Pores are also important in skincare, as they are one of the means in which topical skincare ingredients penetrate into the deeper layers of the epidermis to perform their purpose,” she says. That’s the reason you must clean your skin prior to applying moisturizers. Doing so removes makeup and dirt, but it also cleanses the pores and allows for better product absorption.

In any case, the primary skincare issue surrounding pores is that sometimes they excrete too much sebum, which can cause enlarged pores. Also, when oil mixes with dirt and bacteria, it can result in acne or can make your pores look darker (more on that soon). There are also cases where pores don’t secrete enough oil, which becomes more common as we get older. This leads to dry skin, which can look dull, flaky, and generally unhealthy (heavy moisturizers and oils can fix that problem).  

Cleary, there’s a very fine balance we must achieve to keep our pores happy. The problem? Finding that balance is easier said than done. Getting informed is the first step.

Mythbusting: Pore Edition
Let’s dig right in. These are the three most common myths about pores:

• Those black dots on your nose aren’t blackheads

  There’s a lot of confusion when it comes to blackheads. Blackheads are a form of acne, and specifically a hardened plug of sebum and dead cells within a pore. It looks black because it’s been oxidized (exposed to the air). An extracted blackhead has a black, waxy head with a white or transparent tail. Those gray, pinhead-sized dots you see on your nose and cheeks are most likely sebaceous filaments, not blackheads. When extracted, they look like fine, white or yellow hairs. You can reduce the appearance of sebaceous filaments by cleansing regularly and sticking to a routine, but they will consistently come back as they’re your skin’s way of channeling oil to your face.

• You can’t open and close pores

  Any advice that says you can open or close your pores is wrong. “Pores are not muscles,” explains Dr. Tsippora Shainhouse, a dermatologist and clinical instructor at the University of Southern California. “Hot water and steam will not open your pores, and cold water will not close them. A quick, cool rinse before popping out of the shower will definitely leave your skin looking less pink (it will close the blood vessels), but it won’t change your pore size.”

• You cannot permanently shrink your pores

  The size of your pores is based on genetics, much like the size of your feet or the color of your hair. You can temporarily dye your hair, and you can temporary change your pore size by taking care of them and ridding them of oil and grime, but don’t fall for gimmicks or treatments that promise to permanently change their size.

The Proper Pore Treatment

We get it. At the end of the day, you just want to know how to make your pores appear smaller and keep acne at bay. You can start by cleansing your face every single night—no matter how exhausted you are—to remove dirt, makeup, excess oil and anything else that’s setting up camp in your pores and making them appear larger.

We recommend a double or triple cleanse that starts with an oil cleanser, moves on to a foam cleanser, and follows up with a cleansing water or cleansing tissue just to ensure every last trace is removed from your skin. A good oil cleansing option is Klairs Gentle Black Deep Cleansing Oil, which combines black bean, black currant, and black sesame seed oils to deeply sweep through pores and remove anything sitting on top of your skin. Follow up with Skinfood Egg White Pore Foam, which gently purifies the pores and doesn’t completely strip the skin of important oils. Our current favorite cleansing water is Son & Park Beauty Water ($30), which mildly exfoliates and brightens in addition to cleansing. It also contains willow bark.

“Willow bark and charcoals will dry and mattify the skin, remove some of the surface oils in the pores, and act as a mild exfoliant and pore cleaner,” explains Dr. Shainhouse. “All of these effects will make the pores appear smaller.”

Additionally, applying a primer under your bb cream will help create a smooth base and diminish the appearance of your pores, says Shainhouse. She recommends a silicone or dimethicone-based primer, such as Banila Co Prime Primer Classic. You can also dab away oil throughout the day with blotting tissues, and wear a finishing powder. We like Son & Park’s Flawless Pore Pact.

Finally, Shainhouse says you should apply a topical retinoid in the evenings.

“This has been scientifically demonstrated to increase cell turnover, unclog pores, and encourage new collagen growth, which can strengthen the tissue surrounding the pores so that they appear tighter and smaller,” she explains.

That was a lot of information, but hopefully you’re feeling informed and empowered! Let us know if you have any questions about pores or product recommendations in the comments below and we’ll help you out!

What Are Pores? – Definition & Function – Video & Lesson Transcript

Mammal & Bird Skin

Let’s start off by looking at the pores that everyone is familiar with, the pores of our skin. Mammals (like humans, cats, dogs, monkeys, etc.) all have two types of pores that exist in various proportions, depending on the species. Sweat ducts are pores that excrete sweat, while hair follicles are pores that body hairs pass through.

Your sweat glands are essentially a biological A/C system, responsible for cooling our bodies by secreting watery sweat, which evaporates in the air and cools our skin. Our hair follicles, on the other hand, are the pores that hairs grow in, as well as the opening that allows them to protrude from our skin. Did you know that hair follicles are also the very same pores used by oil producing sebaceous glands? I know that, more often than not, people blame these little pores for blemishes and pimples, but they actually serve a really important purpose – they moisturize your skin as well as offer a level of water repellency via the oily secretions. This is why areas like your face (that have many fine hairs) as well as the hair on your head get so greasy when not washed. Each hair follicle has its own sebaceous gland attached to it. These glands are analogous to a birds preen glands, which secrete oils that they disperse throughout their feathers when they preen, giving them the water-proofing quality with which we are so familiar.

Lactiferous ducts, or lactating ducts, are another type of specialized skin pore that all mammals (referring to organisms with mammary glands, or milk producing glands) have, which secrete milk to feed their young. Men have lactiferous ducts as well, however, they are underdeveloped, and they lack the necessary hormones in the appropriate quantities to actually produce and secrete milk.

Feeding, Ambulatory, & Reproductive Pores

Sponges have little water intake pores, called ostia, that they use to draw water into their tissue for feeding. Once the water enters through these pores, it passes into either little canals, called radial canals, or into a main cavity, called the spongocoel, where little filtering cells sit. These filtering cells snatch little organic particulate out of the water. Sponges are such amazing natural water purifiers that they can filter up to 20,000 times their own volume in water.

Starfish, sea urchin, and sea cucumbers all belong to a group of organisms called echinoderms. Echino means spiny and derms refers to the skin. These creatures utilize a water intake pore, called a madreporite, that they use to flood a series of internal tubules which provide them with a hydrostatic (meaning a fluid-balanced) skeleton. Did you know that this is actually how they move their little tube feet? They flood their hydrostatic skeleton, filling little canals running the length of their bodies as well as their hundreds of tube feet, with water that they then swing in an ambulatory (walking) motion via muscle contractions. Pretty cool, huh?

Insects, spiders, crustaceans, and many parasites, like tapeworms, have gonadopores, or reproductive pores, on the outside of their body. In males, this pore forms the ejaculatory duct, or the passageway that sperm exits the body, whereas in females, it is the oviduct, or the passageway from the ovaries to the outside of the body.

Respiratory, Sensory, & Cellular Pores

Gastropods, like terrestrial snails and slugs, have little breathing pores, called pneumostomes, which they use to draw air into their single lung for oxygen intake.

Some pores are used to sense the environment, such as the little pores that dot the nose of a shark, called ampullae of Lorenzini, that allow them to sense temperature gradients as well as electrical impulses, such as the muscle contractions of prey swimming nearby. The lateral line is a similar organ, formed by a series of pores that enable fish to sense vibration and movement in their watery environment.

Cells have both passive channels, such as those used in the process of osmosis and diffusion, and active channels, which require energy to actively transport ions or water across the plasma membrane.

Plants & Porous Mediums

Yup, that’s right, even plants and rocks have pores! Plants have little pores along their leaves and stems, called stomata, that they use to draw air in for use in photosynthesis and respiration. They then release their metabolic wastes (oxygen and water) back through the pores and out into the environment.

Porous mediums, such as rocks, ceramics, and cement, as well as things like wood and bone, all have little pores or tiny spaces that air and water may pass through. Some of these, such as those used as building materials, require some form of sealing from the elements to protect them from degrading over time.

Lesson Summary

Pores are tiny little openings in the exterior surface of an organism’s skin or a structure. In mammals and birds, pores take the form sweat ducts, hair follicles, and lactiferous ducts in mammals and preen glands in birds. While these pores tend to be secretory, not all function in this way.

Pores fill a variety of specialized functions, such as:

• Feeding: such as the ostia of sponges
• Intake valves: such as the madreporite of starfish and sea urchins that provide structural rigidity to their hydrostatic skeleton
• Reproduction: gonadopores of insects, spiders, and crustaceans
• Respiratory: such as pneumostomes of gastropods and stomata cells of plants
• Sensory: such as the lateral line and ampullae of Lorenzini of sharks and fish

Cells have their own system of pores that may either be passive (as in the case of osmosis and diffusion channels) or active (such as ion and water channels). Materials, such as wood, cement, brick, rocks, and bone are also considered porous, as they have many tiny spaces within their structural matrix through which water and air can pass.

The nuclear pore complex: understanding its function through structural insight

Molecular Expressions Cell Biology: Nuclear Pores

Nuclear Pores

The nuclear envelope is perforated with tiny holes known as nuclear pores, which were first discovered in the mid-twentieth century. These pores regulate the passage of molecules between the nucleus and cytoplasm, permitting some to pass through the membrane, but not others. Building blocks for manufacturing DNA and RNA are some of the materials that are allowed into the nucleus, as are molecules that provide the energy for constructing genetic material. Ribosomal subunits, which are built in nucleosomes, are a prime example of materials that must be allowed to leave the nucleus and enter the cytoplasm.

Nuclear pores are fully permeable to small molecules up to the size of the smallest proteins, but form a barrier keeping most large molecules out of the nucleus. Yet, some larger proteins, such as histones, are granted admission into the nucleus despite the fact that that the pores should be too small to let them through. It is generally thought that the elaborate protein structure called the nuclear pore complex (see Figure 1) that surrounds each pore plays a key role in allowing the active transport of a select set of large molecules into and out of the nucleus.

The nuclear pore complex is comprised of several subunits. Surrounding the inside of the pore is a nonmembranous material organized into an annulus that extends spoke-like structures toward the center of the small channel. The actual pore wall is predominantly comprised of columnar subunits, and lumenal subunits, with the help of transmembrane proteins, anchor the entire pore complex into the nuclear envelope. Also, tiny fibrils usually extend form both sides of the complex and congregate into basket-like configurations on the nuclear side of the complex. The proteinaceous composition of these fibrils is different on opposing sides of the structure.

In addition to their role in nuclear transport, nuclear pores are important as sites where the outer membrane and inner membrane of the nuclear envelope are fused together. Due to this fusion, the membranes can be considered continuous with one another although they have different biochemical characteristics and can function in distinctive ways. Since the outer nuclear membrane is also continuous with the membrane of the endoplasmic reticulum (ER), both it and the inner nuclear membrane can exchange membranous materials with the ER. This capability enables the nuclear envelope to grow bigger or smaller when necessary to accommodate the dynamic contents of the nucleus.

Illustrated in Figure 2 is a fluorescence digital image of an adherent culture of Madin-Darby canine kidney cells (MDCK line) stained with fluorescent probes targeting the nucleus (blue), nuclear pore complex proteins (red), and the tight junctions formed between epithelial cells (green) to demonstrate the proximity of these structures. The nuclear pores of these cells were targeted with a wide-spectrum polyclonal antibody to a large family of nuclear pore complex proteins, which serves as a useful tool for studying the morphology and composition of the nucleus and nuclear envelope. The antibody mixture is also useful in studying changes in the nuclear structure during mitosis and meiosis (note the mitotic cell in the lower central portion of Figure 2).

Pore density varies greatly and tends to be greatest among cells that are highly activate and differentiated, such as liver cells. A typical mammalian cell features approximately 3,000 to 4,000 pores along its nuclear envelope. The oocytes of certain amphibians, however, have such large nuclei and such a density of pores that the nuclear envelope of one of the cells may contain more than ten million pores. Consequently, these oocytes have been heavily utilized in studies of nuclear pore complexes and nuclear transport.

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The nuclear pore complex – structure and function at a glance

ABSTRACT

Nuclear pore complexes (NPCs) are indispensable for cell function and are at the center of several human diseases. NPCs provide access to the nucleus and regulate the transport of proteins and RNA across the nuclear envelope. They are aqueous channels generated from a complex network of evolutionarily conserved proteins known as nucleporins. In this Cell Science at a Glance article and the accompanying poster, we discuss how transport between the nucleoplasm and the cytoplasm is regulated, what we currently know about the structure of individual nucleoporins and the assembled NPC, and how the cell regulates assembly and disassembly of such a massive structure. Our aim is to provide a general overview on what we currently know about the nuclear pore and point out directions of research this area is heading to.

Introduction

A defining difference between eukaryotic and prokaryotic cells is the evolution of an endomembrane system and the presence of a nucleus, resulting in the separation of the genetic material from the rest of the cell. By restricting access to the nucleus and separating gene transcription from protein translation, eukaryotic cells have evolved to control gene expression in a highly regulated manner. Although separated by the double-membrane nuclear envelope, the interior of the nucleus is not completely isolated. Embedded throughout the nuclear envelope are large protein complexes known as nuclear pore complexes (NPCs) that sit in circular openings where the outer nuclear membrane is fused with the inner nuclear membrane. Proteins and RNA can cross the nuclear envelope in a tightly regulated process by traveling through these aqueous protein channels. NPCs are considered to be the gatekeepers of the nucleus and facilitate almost all transport between the nucleoplasm and cytoplasm.

The nuclei of HeLa cells – the commonly used human tissue culture cell line – contain on average 3000 NPCs (Dultz and Ellenberg, 2010; Maul et al., 1972). A single NPC comprises ∼500, mainly evolutionarily conserved, individual protein molecules that are collectively known as nucleoporins (Nups) (Alber et al., 2007). A fully assembled human NPC has an estimated molecular mass of ∼125 MDa (Reichelt et al., 1990), making it one of the largest protein complexes in the cell. Despite its size, the NPC is generated from a limited number of Nups (∼30) that appear in multiple copies (see poster, ‘NPC composition and NPC-deletion phenotypes’). Since the discovery of the NPC more than 60 years ago (Callan and Tomlin, 1950), much has been learned about its composition, structure and function.

In this Cell Science at a Glance article and accompanying poster, we examine how nuclear transport is regulated and highlight the key differences between the transport requirements of proteins and different types of RNA. We discuss some common protein folds found in many Nups and how they contribute to the overall NPC structure and barrier function, before discussing recent discoveries that show evolutionary links between Nups and vesicle coats, and Nups and nuclear transport receptors (NTRs) (see Box 1). Finally, we will review how the cell orchestrates and regulates the assembly of the NPC at different times in the cell cycle. For the purpose of readability, we predominantly use the human nucleoporin nomenclature to address those evolutionarily conserved properties of the NPC that are likely to apply to NPCs of all eukaryotes; we use the fungal nomenclature only when addressing specific aspects that are different when comparing eukaryotic lineages. A brief overview of NPC function, structure and assembly is provided, and more-detailed reviews regarding specific aspects of NPC biology are referenced throughout the text.

The nuclear import–export cycle

Whereas metabolites, ions and molecules smaller than ∼40 kDa can pass freely across the nuclear envelope, larger macromolecules (e.g. proteins, mRNA, tRNA, ribosome subunits and viruses) typically cannot diffuse, but must be actively transported through the NPC (Görlich and Kutay, 1999; Weis, 2003). Each class of macromolecule has a specific way in which it is transported across the nuclear envelope.

The import and export of proteins across the nuclear membrane is regulated by a cycle of interactions between protein cargo, NTRs (e.g. importins, exportins, transportins and karyopherins) and the small GTPase Ran, which regulates the ability of both importins and exportins to transport their cargo (see poster ‘Nuclear import and export pathways – an overview’). For a protein to actively pass through the NPC, it must contain a nuclear localization signal (NLS) sequence. Although the NLS can be complex, the classic NLS is a stretch of basic residues (i.e. KKKRK) (Kalderon et al., 1984). Simply adding an NLS to a non-nuclear protein is often sufficient to localize that protein into the nucleus (Goldfarb et al., 1986). Recognition of the NLS of a cargo is the first step in assembling an import-complex. Canonical nuclear import involves the recognition of the NLS by the adaptor protein importin-α, followed by binding of the karyopherin importin-β, thereby forming a trimeric import complex (Cook et al., 2007; Fried and Kutay, 2003; Stewart, 2007b). Importin-β acts as the transport factor and carries the cargo through the NPC. In other cases, such as when the cargo contains an atypical NLS, importin-β binds to the cargo directly (Cingolani et al., 2002; Lee et al., 2006; Lee et al., 2003). Through either direct interaction with the NLS or through an adaptor protein, the NTRs ultimately determine which cargo is permitted to pass through the nuclear pore.

Fluorescent microscopy studies have shown that translocation through the pore is a rapid process with first-order kinetics, which occurs at a rate of ∼1000 translocations every second (Ribbeck and Görlich, 2001; Yang et al., 2004). Interestingly, the pore itself does not determine the directionality of the import complex. In fact, the movement of the import complex within the pore appears to be random. The directionality of cargo import is determined by a gradient of nuclear RanGTP. Once an import complex enters the nucleus, RanGTP binds importin-β, which releases the cargo. The importin-β–RanGTP complex itself is transported back to the cytosol, disassembled by GTP hydrolysis and ready for the next round of import. Because a dynamic equilibrium of the import complex is maintained in the pore, disassembly of the complex in the nucleus results in a net flow of cargo towards the nucleoplasm. This directional flow is dependent on a RanGTP gradient, whereby the concentration of RanGTP is greater in the nucleus than in the cytosol. This RanGTP gradient is maintained by a Ran guanine nucleotide exchange factor (GEF) that is preferentially located in the nucleus and by RanGTPase-activating proteins (GAPs) in the cytosol (Stewart, 2007b).

Conceptually, the export of proteins from the nucleus occurs in an process that is analogous to nuclear import but reversed (see poster, ‘Nuclear import and export pathways – an overview’). An export complex forms inside the nucleus between cargo displaying a nuclear export signal (NES) – typically a sequence that is leucine rich – a cognate export karyopherin and RanGTP (Ossareh-Nazari et al., 2001). This ternary export complex enters the NPC and, upon exiting the nuclear pore, encounters RanGAP – the Ran-specific GTPase-activating protein – that catalyzes GTP hydrolysis, resulting in disassembly and the release of the cargo (Cook et al., 2007). Also here, the established RanGTP gradient is the driving force for the directionality and nuclear export of proteins.

RNA export

The export of some classes of RNA is similar to the export of proteins. For example, tRNAs and small nuclear RNAs (snRNAs) use the RanGTP gradient and are transported through the NPC by their specific karyopherins exportin-t and Crm1, respectively (Cook and Conti, 2010; Rodriguez et al., 2004). The export of mature ribosomal subunits is also dependent on the RanGTP gradient and uses karyopherin-like transport receptors. However, because of the size of the ribosome, the precise process is still under intense investigation and, overall, remains poorly understood (Panse and Johnson, 2010; Tschochner and Hurt, 2003; Zemp and Kutay, 2007).

The export of mRNA is considerably different from that of proteins and other RNAs. mRNA is not exported alone but, instead, as a large messenger ribonucleoprotein (mRNP) complex, in which a single mRNA molecule is surrounded by hundreds of proteins that have a function in processing, capping, splicing and polyadenylation. The export of mRNPs, thus, presents the cell with a new set of challenges because (1) the diameter of the mRNP cargo is extremely large, (2) the cell must be able to distinguish between correctly (mature) and incorrectly (immature) packaged RNPs, and (3) the mRNA within the RNP may adopt topologies that need to be remodeled before translation can occur (Grünwald et al., 2011).

To overcome these unique challenges, cells have developed a separate mode for transport of mRNPs through the NPC. Before an mRNP particle can enter the NPC, a quality control step is performed by members of the TRAMP (Trf4–Air2–Mtr4p polyadenylation) and exosome protein complexes, which survey mRNA, and identify and degrade any defective mRNPs (Chlebowski et al., 2013; Makino et al., 2013). A mature mRNP is then recruited to the nucleoplasmic side of the NPC or – more specifically – the nuclear basket (see below) by the TREX2 (transcription-export complex 2) and THO complexes. This occurs co-transcriptionally and TREX2 and THO complexes are, therefore, essential in linking active gene transcription to mRNA export (Köhler and Hurt, 2007).

Once a mature mRNP is assembled and targeted to the NPC, it is transported through the channel by a non-karyopherin transport receptor, the Nxf1–Nxt1 heterodimer (Mex67-Mtr2 in yeast) (Grüter et al., 1998; Segref et al., 1997; Stewart, 2010). Although the exact stoichiometry is unknown, several Nxf1–Nxt1 heterodimers bind to the mRNP. Nxf1 and Mex67 neither bind to Ran nor do they use the RanGTP gradient that is crucial for protein transport. Instead, mRNA export (see poster, ‘Export of mRNPs’) is driven by ATP rather than GTP hydrolysis. The energy is required to establish transport directionality by remodeling the mRNP once it reaches the cytoplasm (Stewart, 2007a). Inside the central NPC channel, the mRNP can move forward and backward. However, once part of the mRNP reaches the cytoplasmic face of the NPC, the DEAD-box RNA helicase Dbp5 (also known as SON in humans), whose activity is regulated by the nucleoporin Gle1 and inositol hexaphosphate (IP₆), binds to the mRNA and alters the structure of the mRNP, thereby removing the transport receptor Nxf1–Nxt1 heterodimer in an ATP-dependent manner (Montpetit et al., 2011; Tran et al., 2007; Weirich et al., 2006). Removal of Nxf1–Nxt1 prevents the respective part of the mRNP from returning to the central channel. By repeating this process, the mRNP is fully extracted out of the pore into the cytoplasm. For a more in-depth review of the process, see (Bonnet and Palancade, 2014; Oeffinger and Zenklusen, 2012).

The FG barrier

The NPC is an extremely versatile protein complex as it has to enable the selective transport of both proteins and mature RNA with sizes that range from 40 kDa to entire ribosomal subunits, while preventing other molecules of similar sizes from passing. How does the NPC create a barrier while regulating nuclear transport? This question still remains an intensely debated topic in the field. One issue that is agreed upon is that the regulatory function of the NPC is achieved by a subset of specific Nups, collectively known as FG-Nups. FG-Nups typically contain a structured domain that serves as an NPC anchor point, from which a largely unstructured, filamentous and hydrophilic extension emanates, which is studded with multiple (5–50) hydrophopic phenylalanine–glycine (FG)-repeats (Terry and Wente, 2009).

Over the past decade, a number of models have been proposed on how FG-Nups form the transport barrier (Lim et al., 2007; Patel et al., 2007; Peters, 2005; Ribbeck et al., 2002; Rout et al., 2003). Recent work has provided strong evidence for the so-called ‘selective-phase model’ (Hülsmann et al., 2012; Labokha et al., 2013). In this model, FG-Nups line the central channel and extend their FG-repeat regions into the middle of the channel. The high local concentration of FG-repeats due to the many FG-Nups that localize to the channel (∼200 FG-Nups per channel) generates a hydrogel, in which the FG-repeats bind cohesively to form a ‘sieve’ with mesh size of ∼5 nm. A macromolecule larger than ∼5 nm (∼40 kDa) passes through this barrier by means of a transport receptor that has the ability to bind the FG-repeats, thereby locally ‘melting’ the FG-mediated sieve. The selective-phase model has shortcomings because it does not yet explain the interplay between the different FG nucleoporins; moreover, it is largely based on in vitro data using one FG-protein at the time. Also, many FG-Nups are – for so-far-unknown reasons – heavily glycosylated. Finally, the influence of NTRs as possible constitutive elements of the FG barrier is still mostly unexplored. Thus, the FG barrier remains a central research topic that is passionately and controversially discussed (Atkinson et al., 2013; Kapinos et al., 2014; Peters, 2009; Yamada et al., 2010; Zilman et al., 2010).

NPC structure

The NPC is one of the largest protein complexes in the cell and easily recognizable using scanning electron microscopy (EM). Early EM studies revealed an eightfold rotational ring symmetry for the entire structure. In addition, the main NPC structure contains rings that are situated on its cytoplasmic and nucleoplasmic sides, giving the NPC an apparent twofold symmetry across the nuclear membrane (Beck et al., 2004; Stoffler et al., 2003). A recent electron tomographic study has delineated the structure of the core NPC scaffold at a resolution of 3.2 nm (Bui et al., 2013). This work, together with other studies, shows that the NPC has a thickness of ∼50 nm, an outer diameter of ∼80–120 nm and an inner diameter of ∼40 nm (Bui et al., 2013; Grossman et al., 2012; Maimon et al., 2012). In addition, the obtained images reveal that the NPC contains a structure, resembling a basket that extends into the nucleoplasm (the nuclear basket) and filaments that extend into the cytoplasm (referred to as cytoplasmic filaments).

Despite its enormous size, the NPC is made up of only ∼30 Nups that are largely conserved throughout eukaryotic evolution (Cronshaw et al., 2002; DeGrasse et al., 2009; Rout et al., 2000). Nups are organized into subcomplexes that are biochemically defined by their affinity to each other. In humans, the Nup62 complex comprises Nup62, Nup58 (Uniprot ID: Q9BVL2) and Nup54, all of which contain FG-repeats and are found in the central pore (Finlay et al., 1991; Grandi et al., 1993; Hu et al., 1996) (see poster, ‘NPC composition and NPC-deletion phenotypes’, for corresponding Nup nomenclature in budding yeast Saccharomyces cerevisiae). Nup62 is also a member of the human Nup214 subcomplex, where it interacts with Nup88 and the FG-containing Nup214, and is located on the cytoplasmic side of the NPC (Fornerod et al., 1997; Macaulay et al., 1995). Two other essential subcomplexes provide the structural scaffold for the entire NPC and serve as adaptor proteins that link the FG-Nups to the nuclear membrane. The first is the Y-complex that, in several EM studies, was shown to be elongated and branched, resembling the letter Y – hence its name (Bui et al., 2013; Kampmann and Blobel, 2009; Lutzmann et al., 2002). In humans, this subcomplex contains ten proteins, Nup107, Nup85, Nup96, Nup160, Nup133, Sec13, Seh2, Nup37, Nup43 and ELYS (Loïodice et al., 2004; Lutzmann et al., 2002; Rasala et al., 2006; Siniossoglou et al., 1996). Another NPC subcomplex is the Nup93 complex, which comprises Nup93, Nup188, Nup205, Nup155 and Nup35 in humans (Vollmer and Antonin, 2014). Although the structure of the entire Nup93 subcomplex is still unknown, the individual structures of all its components have been published. Surprisingly, even though the NPC spans two membranes (the outer- and inner-nuclear membrane), only four of the human Nups contain transmembrane (TM) domains, namely Ndc1, Gp210, TMEM33 and Pom121. Biochemical data indicate that these TM proteins connect to the NPC scaffold through the Nup93 complex (Eisenhardt et al., 2014; Mitchell et al., 2010; Yavuz et al., 2010).

A high-resolution structure of the NPC, in which the position of each individual protein is resolved, is a formidable goal for structural biologists. Efforts over the past decade have shown that a hybrid approach using different experimental and computational methods is likely to be needed to fulfill this goal (Alber et al., 2007; Bui et al., 2013).

Assembly and disassembly of the NPC

In addition to being one of the largest protein complexes in the cell, the structural scaffold of the NPC is also one of the longest lived (Savas et al., 2012). Whereas most mammalian proteins have an average half-life of a few days (Cambridge et al., 2011; Price et al., 2010), recent whole animal pulse-chase experiments demonstrated that, in postmitotic tissues, the structural scaffold of the NPC, or at least components thereof, persists over the entire lifetime of a cell (Toyama et al., 2013). In dividing cells, NPCs undergo a cycle of assembly and disassembly that is in concert with the cell cycle. NPC assembly occurs during two stages of the cell cycle, in interphase and immediately after mitosis.

During interphase, the nuclear envelope increases its surface area, and the number of NPCs doubles in preparation for mitosis and to allow the cell to handle the concomitant increase in transcription that necessitates additional mRNA export as well as synthesis and import of histones. These new NPCs form de novo and assemble from both sides of the intact nuclear envelope (D’Angelo et al., 2006).

A model for NPC assembly in interphase has been proposed on the basis of several studies, in which the members of the Nup93 subcomplex are first recruited to the TM-Nups (Flemming et al., 2009; Makio et al., 2009; Onischenko et al., 2009). This association, facilitated by membrane-deforming proteins (e.g. reticulons) then bends the outer- and inner-nuclear membrane toward each other until they eventually fuse (Dawson et al., 2009). Live-imaging kinetics studies have shown that members of the Y-complex also appear around this time (Dultz and Ellenberg, 2010). The localization of the Y-complex during assembly, and NPC assembly itself, is dependent on the components of the Ran cycle and importin-β (D’Angelo et al., 2006; Ryan and Wente, 2002; Ryan et al., 2003; Ryan et al., 2007). Finally, after all the scaffolding Nups have been assembled, the FG-Nups are localized to the NPC, generating the transport barrier.

For post-mitotic NPCs assembly it is important to consider the vast differences between the fate of the nuclear envelope in different organisms. In S. cerevisiae, the nuclear envelope remains closed throughout mitosis, as the microtubule organizing center (MTOC) is embedded in it. In many other organisms, MTOCs are cytoplasmic, which necessitates the nuclear envelope to break down for correct chromosome segregation to occur. Between these extremes of ‘open’ and ‘closed’ mitosis, there are a number of cell types that undergo variations of a ‘semi-closed’ mitosis (De Souza and Osmani, 2007; Güttinger et al., 2009). To what extend these variations affect NPC dissembly and/or reassembly, and how this might have generated fundamentally different post-mitotic versus interphase assembly pathways is an ongoing discussion (D’Angelo and Hetzer, 2008; Doucet et al., 2010). However, it is clear that NPCs are fully disassembled during open mitosis (Laurell et al., 2011) and partially disassembled during ‘semi-closed’ mitosis (De Souza et al., 2004).

Post-mitotic assembly of NPCs begins at the same time as the nuclear envelope starts to reform (Schooley et al., 2012). This assembly process is proposed to be initiated by the targeting of the Y-complex to chromatin, which is facilitated by small-DNA-binding motifs (AT hooks) that are predicted to be present in ELYS (Rasala et al., 2008). As with NPC assembly during interphase, Ran – as well as its effectors – and importin-β regulate Nup recruitment to chromatin (Harel et al., 2003; Walther et al., 2003). However, once ELYS is localized to chromatin, assembly continues with the remainder of the Nup107 subcomplex, which interacts with the TM-Nups Ndc1 and Pom121 (Dultz et al., 2008; Rasala et al., 2008). Members of the Nup93 subcomplex are then recruited soon after (Dultz et al., 2008) and thought to assist in membrane fusion and pore stabilization (Eisenhardt et al., 2014; Ródenas et al., 2009). Once all the scaffolding Nups have been incorporated into the pore, the FG-Nups are localized and nuclear pore activity is restored (Dultz et al., 2008).

Despite the overall stability of the NPC in non-dividing cells, NPCs must nevertheless disassemble in order for mitosis to proceed in dividing cells. NPC disassembly is fast and occurs in a stepwise-regulated manner. Although the exact steps and order in which they occur are currently unknown, disassembly does not appear to be a simple reversal of the assembly steps described above (Dultz et al., 2008). The trigger to initiate the disassembly process is the phosphorylation of several Nups by mitotic kinases (e.g. Cdk1) (Glavy et al., 2007; Laurell et al., 2011; Onischenko et al., 2005). Following their phosphorylation and release from the NPC, some nuclear pore subcomplexes also have additional roles in mitosis. For example, the Y subcomplex is localized to kinetochores, and regulates mitotic spindle assembly and chromosome congression (Orjalo et al., 2006; Zuccolo et al., 2007).

Perspectives

The NPC is a multifaceted and intricate protein complex that is essential to all eukaryotic life. In addition to the main function of the Nups in nucleocytoplasmic transport, new roles – especially in the regulation of gene expression – have recently been identified (Texari et al., 2013; Van de Vosse et al., 2013). Therefore, it is not surprising that aberrant functions of Nups and NPCs have been implicated in many and diverse human pathologies, including autoimmune diseases, viral infections, cardiomyopathies and various cancers (Capelson and Hetzer, 2009; Chow et al., 2012; Hatch and Hetzer, 2014; Simon and Rout, 2014). To better understand large, complicated protein complexes such as the NPC, a multipronged approach using hybrid methods is needed. Already, single-particle EM, EM tomography, super-resolution microscopy, crystallography, immunoprecipitation, crosslinking, mass spectrometry and numerous other methods are being used and combined to help to generate a highly detailed model of the NPC and to identify so-far-unknown Nup functions. Given the intensity of research in the field, it seems realistic that we might know the structure of the NPC, including the positions of all scaffold nucleoporins in the foreseeable future. This, in turn, will give researchers the opportunity to specifically address the many aspects of NPC biology, which will no doubt disclose exciting secrets of cell biology.

Box 1. Evolution of the NPC

In addition to the architectural information gained from high-resolution structural studies of the NPC, these experiments have also shed light on the evolution of Nups and the NPC as a whole. It has been hypothesized that the NPC shares common ancestry with vesicle coat complexes, including COPI, COPII and clathrin (Devos et al., 2004). This hypothesis was initially supported by predictions that similar elements of protein structures are found in both vesicle coats and NPCs – mainly β-propellers and α-helical solenoids – and the fact that Sec13 is a bona fide member of both the NPC and a vesicle coat complex (COPII). The proposed evolution from a common ancestor gained further support from high-resolution structural studies, which found that – despite having less sequence similarity – several Nups (Nup85, Nup96, Nup93 and Nup107) as well as vesicle coat proteins (Sec31 and Sec16) contain a conserved tripartite element, the so-called ancestral coatomer element 1 (ACE1) (Brohawn et al., 2008).

Recently, an additional evolutionary link between the NPC and NTRs has been uncovered. The defining characteristic of the karyopherin protein family, which includes importin-α, importin-β and the exportins, is that they all contain superhelical stacked α-helical units, which allows them to interact with FG-repeats and shuttle cargo through the NPC. Structural analysis of Nup188 (M. thermophile) and its mammalian homolog Nup205 (Nup192 in S. cerevisiae and Chaetomium thermophilium), members of the Nup93 subcomplex, showed they also adopt a structure of stacked α-helices (Andersen et al., 2013; Flemming et al., 2012; Sampathkumar et al., 2013; Stuwe et al., 2014). Such superhelical structures are abundant in eukaryotic cells and are used in many functional contexts. However, similar to karyopherins, Nup188 and Nup205/192 were both shown to specifically bind to FG-repeats and to be able to transverse the NPC, characteristics typically associated with NTRs (Andersen et al., 2013).

The evolutionary links between the NPC, coat-proteins and transport receptors that have been provided by high-resolution structural studies might help to better understand how the NPC is formed, how Nups interact with each other and, ultimately, how each Nup functions in nuclear transport.

Acknowledgments

We apologize to the authors whose work we were unable to cite due to space limitations. We thank Allyson Anding for her help in generating some of the figures, Kasper Anderson for critically reading the manuscript and Martin Beck for providing the tomographic figure.

Footnotes

• Competing interests

  The authors declare no competing or financial interests.

• Funding

  This work of our laboratory was supported by the National Institutes of Health [grant number GM077537] to T.U.S. Deposited in PMC for release after 12 months.

• Cell science at a glance

  A high-resolution version of the poster is available for downloading in the online version of this article at jcs.biologists.org. Individual poster panels are available as JPEG files at http://jcs.biologists.org/lookup/suppl/doi:10.1242/jcs.083246/-/DC1.

• © 2015. Published by The Company of Biologists Ltd

90,000 Shrinking pores is a myth. We tell you how to properly care for skin with visible pores

Cosmetics often promise customers to “shrink or tighten pores,” and many believe to the last that masks and creams will do the trick. Let’s explain why this promise doesn’t really work and how to care for skin with wide pores.

Everyone who studied well at school remembers the appointment since the days of biology lessons.These tiny holes in the skin are the excretory ducts of the sebaceous glands – through them, sebum is released to the surface of the epidermis.

Rumor has it that the functions of the pores are more diverse: supposedly through the pores, the skin and the entire body breathe. In fact, skin cells breathe, which are involved in the process of gas exchange, so clogged pores will definitely not cause death from suffocation.

“Clogged pores” and “wide pores” in cosmetology and dermatology are considered identical concepts.Pore ​​size is genetically inherent and depends on skin type If it is dry or, as they say, normal, then the pores are practically invisible. In oily and combination skin, the opposite is true – the pores look wider and often appear as black dots. The fact is that sebum needs more space to excrete, so the pores of this type of skin are initially wide and clearly visible.

Blackheads are open comedones that occur in enlarged pores due to excessive contamination with dead cells and sebum.Oxygen enters the open comedones, due to which the process of oxidation of melanin begins and, as a result, a black color appears.

About the face

Situation “bags”: causes of edema and effective ways to combat

There are other reasons for the appearance of enlarged pores:

– Age-related changes. Over time, the skin produces less collagen and loses its elasticity – the pores do not physically enlarge, but become more noticeable.

– Exposure to ultraviolet radiation. On the one hand, the sun’s rays destroy collagen. On the other hand, they dry out the skin, and it begins to produce more sebum for hydration. Both processes lead to enlargement of the pores.

– Hormones. It is known that before puberty, the pores on the skin are practically inactive. During puberty, the body begins to produce the hormones estrogen and progesterone. The latter stimulates the secretion of sebum, which is why adolescents are often faced with acne, oily skin and enlarged pores.Hormonal imbalances in adulthood lead to similar symptoms.

What to do with enlarged pores?

For a start, forget about photos of girlfriends, bloggers and models whose skin seems perfect – this is the work of retouchers and filters. Pores of any size are considered the norm, and not a deviation from the canons of beauty.

No one has yet succeeded in narrowing pores with the help of cosmetics and salon procedures.Brands can promise anything, but the beauty industry is losing the battle with genetics – making pores smaller forever is impossible.

Proper care of skin with enlarged pores should include cleansing, sebum-regulating and SPF-products to prevent the negative effects of ultraviolet radiation. Sebum control minimizes stress on pores, while cleansing removes impurities.

Frudia, Green Grape Pore Control Cream

European and Asian brands love grape extract especially – the component is universal for the skin due to vitamins, antioxidants and fruit acids in the composition.In the Frudia sebum-regulating cream, grapes were supplemented with bamboo and menthol extracts. They also regulate the secretion of sebum, while providing hydration and starting the regeneration process. The light texture of the cream is ideal for summer care when hot weather does not favor the use of dense products.

Dermalogica, charcoal revitalizing mask

Charcoal is not new in pore cleansing cosmetics, but Dermalogica mask contains another rather curious and rare ingredient – sulfur, which combines antibacterial and exfoliating functions.That is, while the charcoal draws out impurities from the pores, the sulfur kills acne bacteria and promotes skin renewal. When using the mask, it is important not to overdo it. Sulfur has a fairly high pH, ​​so overuse of the product can break the epidermal barrier and cause dryness.

About the face

AHA-, BHA-, PHA-acids and rules for their use for the skin: detailed instructions

Guinot, purifying mattifying mask

Wide pore skin care masks are a fairly popular format.Due to the high concentration of useful components, they act quickly and efficiently. To regulate the work of the sebaceous glands and purify the mask Guinot added a whole antibacterial complex “Sebotsidin”, and for a mattifying effect – a special powder and pumice crumbs, which works as an exfoliant.

Marble Lab Cleansing Facial Cleansing Gel

It is better to use cleansing masks several times a week, and look for gentle cleansers for every day.For those with oily skin, Marble Lab has a moisturizing and mattifying gel that does not break the lipid barrier. In the composition of glycerin and olive oil – it not only cleanses and softens the skin well, but also promotes recovery after exposure to ultraviolet radiation.

NUXE, Cleansing Micellar Foam with Rose Petals

Another gentle skin cleanser is in the NUXE range.Rose Petal Foam is free of parabens and soap – it removes impurities with a vegetable foaming agent made from fruit acids, cottonseed and rose oils. The petals stated in the name belong to three roses at once: pink, black and white. They soften the skin, so that after using the foam, there is no dry feeling.

Ansaligy, bamboo charcoal face mask

Ansaligy mask works in three directions: hydration, lifting and cleansing.Molecules of hyaluronic acid moisturize the skin, a lifting effect is provided by extracts of red algae and cesalpinia fruits, and bamboo charcoal cleanses pores and improves relief. Owners of sensitive skin are advised to wear the mask for no more than 20 minutes, but if your skin is not prone to redness, then you can use it for up to 40 minutes.

90,000 Pore shaping technology | Nitto in Europe (russian)

Pore shaping technology | Nitto in Europe (Russian)

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The technology of pore formation allows polymer substances to foam, which leads to the formation of many pores. Nitto Denko Corporation has developed pore shaping technology for a wide variety of materials. Through unique membrane technology and substance modification, Nitto Denko Corporation produces products with separation and breathability functions, such as water purification membranes and air filters.
Foams used in automobiles, electrical components and other products, which are also made with pore-forming technology, have properties such as damping, waterproofing and sealing.

Separating Membrane Technology

Manufacturing methods for ultrafiltration (UV), microfiltration (MF) and other polymeric membranes are based on phase separation, orientation and etching.Nitto Denko manufactures polysulfone UV membranes using a type of phase separation called induced precipitant phase separation (NIPS). As shown in the figure below, phase separation occurs when a precipitant is used to form a solution to form membranes from polysulfone and solvent, resulting in a porous structure.

Foaming Technology

When foamed, polymers can obtain a wide range of properties and functions such as flexibility, damping, thermal insulation, sound insulation, sound absorption and light weight.A number of foaming agents are commonly used and foaming is accomplished by mechanical gas injection or chemical decomposition of the foaming agent.

By varying the agent and foaming method, the size and volume of the air bubbles, as well as their structure, can be controlled.

Technology for creating porous fluoroplastic film

Fluoroplastics (for example, PTFE), which are used for the production of porous materials, are characterized by fibrinization, while a small shear stress is sufficient to form fibrils (thin fibers).When these fibers are spliced ​​and intertwined, a porous structure (membrane) is formed.

Typically, fluoroplastic porous membranes are created using a technique called orientation to pair and draw fibers. To create pores from fibers, we use biaxial orientation of fluoroplastic in the longitudinal and transverse directions with a high magnification, which allows us to accurately create pores in microscopic fibers.

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90,000 Enlarged pores and oily skin

Thermoregulatory and excretory functions of the skin are carried out with the participation of pores – through them excess fat and sweat are released, and the skin is moisturized and protected from the negative influences of the external environment.If sebum is produced in excess, the pores will expand and become visible. Also, the skin acquires an oily sheen, more often this trouble affects the forehead, nose, chin, less often – the cheeks. This is not only a cosmetic defect. Enlarged pores are the main reason for the accumulation of epithelial cells, fat, impurities in them, which leads to blockage and the formation of acne and microinflammation. In order to avoid creating favorable conditions for the growth of bacteria, it is important to properly care for oily skin.In many ways, care is chosen based on what reasons led to the expansion of pores.

Causes of

Most cases of enlarged pores are due to a hereditary predisposition of the skin to produce excess sebum. However, there are other reasons that may have an impact:

• Changes in hormonal levels – restructuring of the body during adolescence, during pregnancy, breastfeeding, menopause
• Endocrine dysfunction – malfunction of the endocrine glands
• Unbalanced diet, characterized by the predominance of fatty, sweet foods, spices in the diet
• Diseases of the gastrointestinal tract

• Nervous system disorders
• Bad habits – smoking, alcohol abuse
• Improper care for oily skin – selection of cosmetics with a dense, oily texture, inattention to the rules for removing makeup and cleansing the skin
• Use of makeup that is not suitable for skin type

In order to effectively act on the problem, it is important to eliminate the root cause and additionally correct the condition using one or more modern techniques.

Proposed services to solve this problem

THERE ARE CONTRAINDICATIONS, SPECIALIST CONSULTATION IS REQUIRED

BELSORP MAX II – Surface area and pore size distribution

Functions for the implementation of municipal land control up to 8 Crimean municipalities still fail to comply – Alexander Spiridonov | State Committee for State Registration and Cadastre of the Republic of Crimea

17.05.2017

8 out of 27 Crimean municipalities still do not fulfill the functions of municipal land control. This was announced by the Chairman of the State Committee for State Registration and Cadastre of the Republic of Crimea, the Chief State Inspector of the Republic of Kazakhstan for the use and protection of lands, Alexander Spiridonov, commenting on the results of a seminar for officials of local governments on the implementation of municipal control in certain areas, held in the State Council of the Republic of Kazakhstan.The event was attended by the head of the State Land Supervision Department of the Committee Alexander Kostyuk.

The head of the Goskomregister reminded that the functions of implementing municipal land control (MZK) are entrusted to local governments. The main tasks of the MZK are aimed at increasing the efficiency, rational use and protection of land resources in the territory of municipalities. According to him, all municipalities have adopted administrative regulations, developed and approved a regulation on the implementation of municipal land control, but this work has not been established in a number of regions.

“Municipal land control is an effective tool for forming the taxable base of each urban district or rural settlement. Intervention by inspectors can harmonize the collection of land tax and land rent payments, not to mention the payment of fines for violations that eventually go to the local budget. It is clear that these structural divisions of administrations are in fact being formed: somewhere in addition to land control, specialists are additionally assigned other functions, and someone simply does not have the proper equipment to determine the boundaries of land plots and measure the area.Unfortunately, due attention is not paid to this issue everywhere. So, the State Committee for Registration has not yet received a single material of checks from the administrations of Bakhchisarai, Belogorsk, Dzhankoy, Krasnoperekopsk, Feodosia, as well as Leninsky, Krasnoperekopsky and Black Sea regions. This is despite the fact that the Department of the State Land Supervision of the Committee regularly holds meetings, meetings and seminars, providing the necessary methodological assistance to colleagues in the regions, ”the head of the department emphasized.

Run while loop until function returns

I am trying to light a 5mm LED while the function is running.When this function (more on that below) completes and returns a value, I would like to break the while loop.

Current code for while loop :

  pins = [3,5,8,15,16]

def piBoard ():
  finished = 0
  while finished! = 10:
    for pin in pins
      GPIO.output (
        pin, GPIO.HIGH
      )
      time.sleep (0.1)
      GPIO.output (
        pin, GPIO.LOW
      )
    finished + = 1
  

Now, in the above example, I just run the while loop until the count is 10, not best practice.I would like the while loop to break if my next function returns a value.

Function I want to break my while loop when its value returns

  def myFunction ():
  Thread (target = piBoard (). Start ()
  // Trying to recognize the song
  return the song which is recognized
  

Thank you – K.

python

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Source

Kevin Etore

July 25, 2017 at 17:22

5 replies

• While loop collect data from the database until the array contains a certain value

  I am trying to create a while loop in PHP that fetches data from a database and puts it into an array.This while loop should only work as long as its filling array does not contain a certain value. Is there a way to scan the array and look for the value while the loop is still busy? …

• how to stop execution until method returns value in java

  I am almost new to java threading. I have a scenario where I send JSON messages to a rabbitmq queue, and an external service performs an operation on the received JSON, and then after the external service has executed, it returns an integer value indicating whether the execution succeeded or not.I…

1

It looks to me like you want to write a class that extends Thread and implements the methods __enter__ and __exit__ to make it work in statement with . Easy to implement, simple syntax, works pretty well. The class will look like this:

  import threading

class Blinky (threading.Thread):
    def __init __ (self):
        super () .__ init __ ()
        self.daemon = True
        self._finished = False

    def __enter __ (self):
        self.start ()

    def __exit __ (self, exc_type, exc_val, exc_tb):
        self.stop ()

    def run (self):
        # turn light on
        while not self._finished:
            time.sleep (.5)

        # turn light off

    def stop (self):
        self._finished = True
  

Then, to run your function, you simply put:

  with Blinky ():
    my_function ()
  

The light should turn on as soon as statement with is reached, and turn off half a second after exiting the context with .

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Eric Ed Lohmar

July 25, 2017 at 17:43

0

Using a decorator and I / O inspired by @Eric Ed Lomare:

  import asyncio

def Blink ():
    from functools import wraps
    async def _blink ():
        while True:
            print ("OFF")
            await asyncio.sleep (.5)
            print ("ON")
            await asyncio.sleep (.5)

    def Blink_decorator (func):
        @wraps (func)
        async def wrapper (* args, ** kwargs):
            asyncio.ensure_future (_blink ())
            await func (* args, ** kwargs)
        return wrapper

    return Blink_decorator

@Blink ()
async def longTask ():
    print ("Mission Start")
    await asyncio.sleep (3)
    print ("Mission End")

def main ():
    loop = asyncio.get_event_loop ()
    loop.run_until_complete (longTask ())
  

Share

mlyy

July 25, 2017 at 21:14

0

While the condition is true and in the while loop, put an if statement that will check if your function returns any value, if the declaration is written break

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Filippos Ser

July 25, 2017 at 17:26

• Show a progress bar while a function is executing in a loop until it returns a value

  I have a function that triggers an sql query for data that may or may not be there.Since I need to run this function continuously until it returns the correct value, how can I run the progress bar until the loop finishes. status = …

• Java while loop until user enters value 0

  Having trouble creating a while loop that keeps reading user input until 0 is entered. Then the average of all values ​​will be calculated and printed at the end.Here is some of my coding, but it is wrong. Just showing you how I …

0

if you are open to using streams.
you can achieve this with streams.
here is a sample code

  from concurrent.futures._base import as_completed
from concurrent.futures.thread import ThreadPoolExecutor

WORK_FINISHED = False

def piBoard ():
  while not WORK_FINISHED:
    # Do some stuff
    # Drink some coffee

def myFunction ():
  time.sleep (5)
  global WORK_FINISHED
  WORK_FINISHED = True #update gobal status flag
  return something

if __name__ == '__main__':
    futures = []
    MAX_WORKERS = 5 #max number of threads you want to create
    with ThreadPoolExecutor (MAX_WORKERS) as executor:
        executor.submit (piBoard)
        # submit your function to worker thread
        futures.append (executor.submit (myFunction))

    # if you need to get return value from `myFunction`
    for fut in as_completed (futures):
        res = fut.result ()
  

Hope this helps.

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Asav Patel

July 25, 2017 at 17:36

0

You need some kind of inter-thread communication. threading.Event is about as easy as you can get.

  import threading

song_recognized_event = threading.event ()
  

in your song recognizer, call set () as soon as the song is recognized.

In the LED loop, check isSet () from time to time by toggling the LEDs.

  while not song_recognized_event.isSet ():
    # toggle LEDs
  

Run clear () to clear it.

Share

nimish

July 25, 2017 at 17:47

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