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Male parts diagram: Male Reproductive System | SEER Training

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Human reproductive system | Definition, Diagram & Facts

male and female reproductive systems

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Gabriel Fallopius
George Washington Corner
Reinier de Graaf
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human reproductive system, organ system by which humans reproduce and bear live offspring. Provided all organs are present, normally constructed, and functioning properly, the essential features of human reproduction are (1) liberation of an ovum, or egg, at a specific time in the reproductive cycle, (2) internal fertilization of the ovum by spermatozoa, or sperm cells, (3) transport of the fertilized ovum to the uterus, or womb, (4) implantation of the blastocyst, the early embryo developed from the fertilized ovum, in the wall of the uterus, (5) formation of a placenta and maintenance of the unborn child during the entire period of gestation, (6) birth of the child and expulsion of the placenta, and (7) suckling and care of the child, with an eventual return of the maternal organs to virtually their original state.

For this biological process to be carried out, certain organs and structures are required in both the male and the female. The source of the ova (the female germ cells) is the female ovary; that of spermatozoa (the male germ cells) is the testis. In females, the two ovaries are situated in the pelvic cavity; in males, the two testes are enveloped in a sac of skin, the scrotum, lying below and outside the abdomen. Besides producing the germ cells, or gametes, the ovaries and testes are the source of hormones that cause full development of secondary sexual characteristics and also the proper functioning of the reproductive tracts. These tracts comprise the fallopian tubes, the uterus, the vagina, and associated structures in females and the penis, the sperm channels (epididymis, ductus deferens, and ejaculatory ducts), and other related structures and glands in males. The function of the fallopian tube is to convey an ovum, which is fertilized in the tube, to the uterus, where gestation (development before birth) takes place. The function of the male ducts is to convey spermatozoa from the testis, to store them, and, when ejaculation occurs, to eject them with secretions from the male glands through the penis.

At copulation, or sexual intercourse, the erect penis is inserted into the vagina, and spermatozoa contained in the seminal fluid (semen) are ejaculated into the female genital tract. Spermatozoa then pass from the vagina through the uterus to the fallopian tube to fertilize the ovum in the outer part of the tube. Females exhibit a periodicity in the activity of their ovaries and uterus, which starts at puberty and ends at the menopause. The periodicity is manifested by menstruation at intervals of about 28 days; important changes occur in the ovaries and uterus during each reproductive, or menstrual, cycle. Periodicity, and subsequently menstruation, is suppressed during pregnancy and lactation.

This articles describes the organs, both male and female, that are involved in human reproduction. The reproductive process itself is covered in other articles. For a detailed discussion of the series of changes that occur in a woman’s body as her fetus develops, see pregnancy. For a description of the stages of labour and delivery, see parturition. For the development of the unborn child during gestation, see human embryology. For coverage of the many diseases and disorders that can affect the reproductive organs, see reproductive system disease.

Britannica Quiz

The Human Body

The sex of a child is determined at the time of fertilization of the ovum by the spermatozoon. The differences between a male and a female are genetically determined by the chromosomes that each possesses in the nuclei of the cells. Once the genetic sex has been determined, there normally follows a succession of changes that will result, finally, in the development of an adult male or female. There is, however, no external indication of the sex of an embryo during the first eight weeks of its life within the uterus. This is a neutral or indifferent stage during which the sex of an embryo can be ascertained only by examination of the chromosomes in its cells.

The next phase, one of differentiation, begins first in gonads that are to become testes and a week or so later in those destined to be ovaries. Embryos of the two sexes are initially alike in possessing similar duct systems linking the undifferentiated gonads with the exterior and in having similar external genitalia, represented by three simple protuberances. The embryos each have four ducts, the subsequent fate of which is of great significance in the eventual anatomical differences between men and women. Two ducts closely related to the developing urinary system are called mesonephric, or wolffian, ducts. In males each mesonephric duct becomes differentiated into four related structures: a duct of the epididymis, a ductus deferens, an ejaculatory duct, and a seminal vesicle. In females the mesonephric ducts are largely suppressed. The other two ducts, called the paramesonephric or müllerian ducts, persist, in females, to develop into the fallopian tubes, the uterus, and part of the vagina; in males they are largely suppressed. Differentiation also occurs in the primitive external genitalia, which in males become the penis and scrotum and in females the vulva (the clitoris, labia, and vestibule of the vagina).

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At birth the organs appropriate to each sex have developed and are in their adult positions but are not functioning. Various abnormalities can occur during development of sex organs in embryos, leading to hermaphroditism, pseudohermaphroditism, and other chromosomally induced conditions. During childhood until puberty there is steady growth in all reproductive organs and a gradual development of activity. Puberty marks the onset of increased activity in the sex glands and the steady development of secondary sexual characteristics.

In males at puberty the testes enlarge and become active, the external genitalia enlarge, and the capacity to ejaculate develops. Marked changes in height and weight occur as hormonal secretion from the testes increases. The larynx, or voice box, enlarges, with resultant deepening of the voice. Certain features in the skeleton, as seen in the pelvic bones and skull, become accentuated. The hair in the armpits and the pubic hair becomes abundant and thicker. Facial hair develops, as well as hair on the chest, abdomen, and limbs. Hair at the temples recedes. Skin glands become more active, especially apocrine glands (a type of sweat gland that is found in the armpits and groin and around the anus).

In females at puberty, the external genitalia enlarge and the uterus commences its periodic activity with menstruation. The breasts develop, and there is a deposition of body fat in accordance with the usual contours of the mature female. Growth of axillary (armpit) and pubic hair is more abundant, and the hair becomes thicker.

Male sex organs and reproductive system

Diagram of the male reproductive system

The testicles are 2 organs that are covered by a sac of skin
called the scrotum. They produce hormones (mostly testosterone) and sperm.

The male reproductive system is controlled by the pituitary
gland in the brain. When puberty begins, the pituitary gland signals the
testicles by releasing the follicle-stimulating hormone (FSH) and the luteinizing
hormone (LH). The testicles then start to make testosterone and sperm.
Testosterone is responsible for male sexual development, including deepening of
the voice, enlargement of the penis and testicles, growth of facial and body
hair and muscle development.

The epididymis sits on the back of each testicle. It stores sperm cells so they can mature.

The vas deferens carries mature sperm to the urethra for
ejaculation.

The prostate is deep in the pelvis in front of the rectum and
below the bladder. It makes prostatic fluid. Prostatic fluid is rich in enzymes, proteins and
minerals that help protect and nourish sperm. During sex, the prostate pushes
prostatic fluid through the ducts and into the urethra. Prostatic fluid mixes
with sperm and other fluids in the urethra and is ejaculated as semen.

The seminal vesicles are glands found on each side of the
prostate. They make most of the fluid in semen. The seminal vesicles fuse with
the vas deferens to empty into the urethra.

The urethra carries urine (pee) from the bladder to the outside
of the body. It also carries sperm out of the body through the meatus (opening
of the urethra out of the body) during ejaculation.

Diagram of the penis

The penis has 3 parts. The shaft is the main part of the penis. The head of the penis is called the glans. The glans is covered by a loose fold of moveable skin called the foreskin (prepuce). Sometimes the foreskin is surgically removed in an operation called a circumcision. The base of the penis within the pelvis is called the root.

For the penis to penetrate a vagina or an anus during sex, it needs to be erect, or stiff. An erection begins when the brain sends a signal down the spinal cord through the nerves that run to the pelvis. Nerves signal the blood vessels inside of each corpus cavernosum of the penis to fill with blood. When the blood flow increases, the spongy tissue expands and causes the penis to stiffen and enlarge.

During an orgasm, the prostate, seminal vesicles and vas deferens contract to move semen near the top of the urethra and then out during ejaculation. Each ejaculation can release up to 500 million sperm. After ejaculation, the extra blood flows out of the penis and the penis becomes soft again.

For pregnancy, semen ejaculated into a vagina (in the female reproductive system) allows for sperm to swim up through the cervix and uterus into the fallopian tube to meet an egg (if one is there). It only takes one sperm to fertilize the egg. Once fertilized, the egg grows in the uterus becoming an embryo and then a fetus.

  • Tim Rowe, MB BS, FRCSC, FRCOG

  • John Robinson, PhD, R Psych

  • Martini FH, Timmons MJ, Tallitsch RB. Human Anatomy. 7th ed. San Francisco: Pearson Benjamin Cummings; 2012.

  • Cancer Research UK. Men’s Sexual Organs. 2018: https://www.cancerresearchuk.org/about-cancer/coping/physically/sex/mens-organs.

  • American Cancer Society
    . Sex and the Adult Male with Cancer
    . 2021
    : https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/fertility-and-sexual-side-effects/sexuality-for-men-with-cancer/treatment-and-desire-and-response.html.

  • American Society of Clinical Oncology. Sexual Health and Cancer Treatment: Men. 2019: https://www.cancer.net/navigating-cancer-care/dating-sex-and-reproduction/sexual-health-and-cancer-treatment-men.

  • National Cancer Institute. Sexual Health Issues in Men with Cancer. 2018: https://www.cancer.gov/about-cancer/treatment/side-effects/sexuality-men.

  • Cancer Research UK. About Sexuality and Sex Life. 2021: https://www.cancerresearchuk.org/about-cancer/coping/physically/sex/about-sexuality.

  • Cancer Research UK. How Cancer Can Affect Your Sexuality and Sex Life. 2018: https://www.cancerresearchuk.org/about-cancer/coping/physically/sex/effects#.

Anatomy and function of the male reproductive system

In men and women, the genital organs are located both inside the pelvic cavity and outside it. Most of the male reproductive system is located outside. Such a device in wildlife is a demonstration of its strength and superiority. Perhaps this is why many, if not most, men are embarrassed to see a doctor if they have problems in their intimate life.

This article is not to be used for diagnosis, treatment, and is not a substitute for seeing a doctor.

The reproductive system of a man is extremely important, as well as other systems of the body that ensure normal life. Therefore, an untimely appeal to a specialist or, even worse, ignoring the warning signs, creates much bigger problems than they were originally.

The male reproductive system has three main tasks:

  1. Formation of spermatozoa in the testes (seniferous tubules). In the process of one ejaculation, 30-500 million spermatozoa come out.
  2. Evacuation of seminal fluid from the male genital organs and its delivery to the female.
  3. Synthesis of the main androgen (a group of steroid sex hormones in men) – testosterone.