D’YOUVILLE COLLEGE
BIOLOGY 108/508 - HUMAN ANATOMY & PHYSIOLOGY II
LECTURE # 24
REPRODUCTIVE SYSTEM
MALE
1.
Anatomy of Male Reproductive Tract (fig. 27 - 1):
a. Testes: primary sex organs suspended via spermatic cord in scrotum (figs.
27 - 2 & 27 - 3); blood supply: testicular artery surrounded by venous network
(pampaniform plexus) facilitates temperature regulation
• lobules contain seminiferous tubules (site of spermatogenesis)
- endocrine interstitial cells of Leydig (source of androgens)
• epididymis: connects testis with vas deferens (sperm duct); vas passes
into body within spermatic cord & loops medially over ureter to descend posterior
wall of urinary bladder; surgical interruption = 'vasectomy'
b. Accessories: seminal vesicles empty into proximal parts of vasa deferentia;
secrete seminal fluid (approximately 70% of volume of semen)
• prostate gland: receives urethra from urinary bladder and is site of
junction of vasa deferentia with urethra (combined reproductive and urinary
passageway from this point to exterior); secretes prostatic fluid (about 30% of semen)
• bulbourethral glands: join urethra near bulb of penis; secrete mucus
• urethra extends from urinary bladder through prostate (prostatic part),
pierces urogenital diaphragm (membranous part), and passes out penis to exterior
(spongy part); combined reproductive and urinary passageway
c. Penis (fig. 27 - 4): copulatory organ composed of three masses of erectile
tissue:
• corpus spongiosum: features proximal swelling (bulb) and distal swelling
(glans); conveys urethra to exterior; glans covered by prepuce (foreskin)
• corpora cavernosa: dorsal masses; diverge proximally (crura of penis)
2.
Physiology of Male Reproduction:
a. Hormonal Relationships (fig. 27 - 9):
• Gonadotropin Releasing Hormones: regulate pituitary gonadotropins:
• Follicle Stimulating Hormone (FSH): facilitates testosterone binding to
stimulate spermatogenesis in testis
• Luteinizing Hormone (LH): for testosterone secretion (interstitial cells)
• Testosterone: promotes development of primary reproductive structures,
maturation of spermatozoa, development of secondary sex characteristics
(distribution of body hair, muscular hypertrophy, enlargement of larynx)
Bio 108/508
lec. 24 - p. 2
b. Spermatogenesis (fig. 27 - 7): spermatogonia (diploid sperm mother cells) at
periphery of testis ---> primary spermatocytes (diploid cells that enter meiosis I) --->
secondary spermatocytes (haploid cells that enter meiosis II) ---> spermatids
(haploid cells that mature into spermatozoa = spermiogenesis); latter processes occur
in intimate association with nutritive sustentacular (Sertoli) cells
c. Erection and Orgasm: penis (normally flaccid, inferiorly directed) becomes
rigid and erect during sexual excitation--parasympathetic nerve activity causes
hyperemia of erectile tissues = erection (renders penis suitable for intromission and
deposit of semen in female reproductive tract)
• sympathetic nerve signals cause ejaculation (sexual climax)