Module 3 Lesson 1 - 3

Spermatogenesis

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In the early stages, germ cells or gametes are supported, nurtured, and protected by specialized supporting somatic cells. Mature gametes are produced in a process called gametogenesis. In males, gametogenesis is called spermatogenesis — the formation of sperm and the structures that support sperm production. In females, it is called oogenesis — the formation of eggs.

Although women are born with all the eggs they will ever have, men produce sperm on a continual basis. A man's sperm or gamete development can be affected, therefore, by what he does daily. Choices a man makes regarding smoking, stress management, nutrition, exercise, and drug and alcohol use contribute to the production and quality of his sperm. Regardless of the choices he makes, the quality of a man's sperm begins to decline slowly at approximately age 25.

Mature male gametes commonly called sperm are referred to scientifically as spermatozoa. During the stages of development the sperm cells are in close contact with Sertoli cells and interstitial cells.

Sertoli cells are located within the seminiferous tubules in the testes and are sometimes referred to as nurse cells. They nurture the developing sperm cells by providing secretory and structural support. The Sertoli cells give structural support by acting as a barrier to protect the sperm during their development.

Because spermatozoa begin development at puberty, the body considers sperm cells to be foreign to the body. If not protected by the Sertoli cells, the body's immune system would destroy them.

Interstitial cells are located in the testes, but they are not in the seminiferous tubules. Although they are linked indirectly to sperm production, they secrete testosterone, which targets the entire male body and stimulates the development of the male reproductive system, the secondary male sex characteristics, and spermatogenesis.

Male Reproductive System Review

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Number	Structure	Function
1	testes	produce and store sperm, testosterone, and inhibin
2	epididymis	store sperm and provide location for maturation
3	penis	provides means of transferring semen to females (the male organ of reproduction)
4	urethra	transports semen (sperm) and urine in a common duct
5	vas deferens (ductus deferens)	transport sperm from each testis (seminiferous tubules) through the epididymis to the urethra
6	urinary bladder	stores urine, empties into the urethra
7	ureter	transports urine from the kidney to the bladder
8	seminal vesicle	secretes mucus that contains fructose (sugar) as energy for sperm (Fluid is secreted into the duct system. Sperm do not enter the accessory glands.)
9	prostate gland	secretes mucus and alkaline fluid to neutralize the acidic conditions of the urethra (urine) and the vagina (Sperm do not enter the accessory glands.)
10	Cowper's gland	secretes mucus and alkaline fluid to neutralize the acidic conditions of the urethra (urine) and the vagina (Sperm do not enter the accessory glands.)

Watch and Listen

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Watch the section on spermatogenesis in the video clip "Biologix-14: The Male Reproductive System: Perpetuating the Species" to further your understanding of how the structural support tissue helps develop the male gametes