The male reproductive system

Although we are born with the sexual organs (primary sexual characteristics) already formed, it will not be until puberty when they finish maturing and have reproductive capacity. The reproductive system produces sex cells or gametes and secretes hormones that cause the appearance of secondary sexual characteristics. The female reproductive system is also responsible for the development of the new individual.

As a guide, the diagram shows how the reproductive system develops and secondary sexual characteristics appear according to the age and sex of the person. This causes sexual dimorphism, men and women are anatomically different.

The male reproductive system forms the male gamete, the sperm, which is the sex cell that will join the ovum and contains the DNA that the father contributes to the new individual.

Parts of the male reproductive system

By Male_anatomy.png: alt.sex FAQMale_anatomy_all.svg: Tsaitgaist (talk)Spanish version: Angelito7 (Male_anatomy_all.svg) [GFDL or CC-BY-SA-3.0], via Wikimedia Commons

The organs of the male reproductive system are:

• The testicles. They are the male gonads, responsible for producing spermatozoa. They are located outside the abdomen, inside a bag called the scrotum, where their temperature is a couple of degrees lower and more appropriate for the creation of sperm. They also secrete testosterone, the sex hormone that produces the appearance of secondary sexual characteristics in men.
• The epididymis. It is a tube formed by seminiferous tubules, very folded in on itself, located in the upper part of each testicle. Inside it, sperm mature.
• The vas deferens. It is the tube that communicates each epididymis with the urethra. Here sperm are stored until they exit into the urethra.
• The seminal vesicles. Located behind the urinary bladder, these glands discharge seminal fluid into the vas deferens, which serves as a vehicle and food for the sperm.
• The prostate. Gland located under the urinary bladder that surrounds the urethra. It produces prostatic fluid, which serves to neutralize the acidity of the urethra and vagina and stimulate the mobility of sperm.

Video: Prostatic hypertrophy.

• Cowper's glands or bulbourethral glands. Located under the prostate, they have the function of secreting an alkaline liquid that lubricates and neutralizes the acidity of the urethra before ejaculation. This precum may contain some sperm.

The sperm is viscous whitish liquid that is expelled through the urethra during ejaculation, formed by the set of spermatozoa and all substances that are added along the path of the reproductive system.

• The urethra. It is the tube that crosses the penis and that is common to the urinary system and the reproductive system. Urine and semen are expelled through the urethra.
• The penis. It is the copulatory organ, and has the function of depositing semen inside the vagina. The urethra is covered by a tissue, the corpus spongiosum, which widens in the front part forming the glans, a very sensitive area that is covered by a fold of skin, the foreskin. In addition, in the penis there are also two spongy masses of erectile tissue, the corpora cavernosa, located above the urethra.

With sexual arousal, the blood vessels dilate and the corpora cavernosa fill with blood, making the penis stiff (erection) and facilitating penetration into the vagina.

Animation: Male reproductive system.

Activity: Male reproductive system.

Activity: Male genital tract.

Activity: Crossword with the parts of the male reproductive system.

Activity: Male reproductive system.

Activity: Male reproductive system.

Activity: Male reproductive system.

Activity: Male reproductive system.

Test and video: The male reproductive system.

Game: Parts of the male reproductive system.

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Animation: L´appareil reproducteur masculin.

Physiology of the male reproductive system

The process of gamete formation is called gametogenesis and occurs in the gonads (testes and ovaries) from cells existing in these organs that, like the rest of the cells of the human body, have 46 chromosomes. However, there is a process of cell division (meiosis) that causes these cells to divide into others with half the chromosomes (23). Thus, after fertilization, the newly formed cell will again have 46 chromosomes, and from here on, the cells will multiply until giving rise to the new individual with 46 chromosomes, just like their parents.

The gametogénesis male is called spermatogenesis and is made in the testicles. Unlike women, men begin to produce gametes at puberty and will do so throughout their lives.

The following scheme represents spermatogenesis:

By OpenStax College [CC BY 3.0], via Wikimedia Commons

From spermatogonia, cells with 46 chromosomes, spermatozoa with 23 chromosomes are produced.

The formation of gametes, ovules and spermatozoa is controlled by the endocrine system. Furthermore, the testes also act as endocrine glands.

Activity: Physiology of the male reproductive system.

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