Essentials of Anatomy and Physiology

460 The Reproductive Systems

Spermatic cord

Testicular artery

and veins

Ductus deferens

Nerve

Rete testis

Capillaries Epididymis

Interstitial cells

Sustentacular cell

Lumen

Seminiferous

tubules

Spermatozoa (sperm cells)

Spermatids

Spermatocytes

Spermatogonia

B A

Figure 20–4. (A) Midsagittal section of portion of a testis; the epididymis is on the pos-

terior side of the testis. (B) Cross-section through a seminiferous tubule showing develop-

ment of sperm.

QUESTION:Trace the pathway of sperm from their formation to the ductus deferens.

Table 20–1 HORMONES OF MALE REPRODUCTION

Hormone Secreted by Functions

FSH

LH (ICSH)

Testosterone*

Inhibin

* In both sexes, testosterone (from the adrenal cortex in women) contributes to sex drive and muscle-protein synthesis.

Anterior pituitary

Anterior pituitary

Testes (interstitial cells)

Testes (sustentacular cells)

• Initiates production of sperm in the testes


• Stimulates secretion of testosterone by the testes


• Promotes maturation of sperm


• Initiates development of the secondary sex characteristics:
  —growth of the reproductive organs
  —growth of the larynx
  —growth of facial and body hair
  —increased protein synthesis, especially in skeletal muscles


• Decreases secretion of FSH to maintain constant rate of spermatogenesis