Biology 12

194 MHR • Unit 2 Homeostasis

Male Reproductive Hormones

The process of spermatogenesis is stimulated by

the FSH from the anterior pituitary gland. The

seminiferous tubules, in addition to producing

sperm, release the hormone inhibin, which forms a

negative feedback loop with FSH (shown in Figure

6.25). Inhibin acts on the hypothalamus to slow the

production of the releasing factors that control the

release of FSH. The interaction of FSH and inhibin

controls the rate of formation of sperm.

Another hormone from the anterior pituitary,

LH (luteinizing hormone), stimulates the interstitial

cells of the testes that surround the seminiferous

tubules. These cells produce the male sex

c.

acrosome

head

middle piece

tail

uncoiled

seminiferous

tubule

sperm

cells

interstitial cells

nucleus of

Sertoli cell

spermatogonium

primary spermatocyte

secondary

spermatocyte

spermatid

vas deferens

epididymis

testis

scrotal sac

cross

section

of

seminiferous

tubule

A

B C

D

Figure 6.24(A) The lobules of a testis contain seminiferous

tubules. (B) Light micrograph of a cross section of

seminiferous tubules, where spermatogenesis occurs.

(C) Diagram of spermatogenesis, which occurs in the wall

of the tubules. (D) A sperm has a head, a middle piece, and

a tail. The nucleus is in the head, capped by the enzyme-

containing acrosome.