leaked from the male reproductive tract are viewed as foreign by immune
surveillance and antibodies develop. The phagocytosis of sperm by
macrophages plays a role in the development of antisperm antibodies that
occurs following the ligation or removal of a segment of the vas deferens
(answer d).Sperm are immunologically foreign because of a number of
factors.
Spermatogenesis begins at puberty long after the development of self-
recognition in the immune system (answer b).The blood-testis barrier
protects developing sperm from exposure to systemic factors (answer a).
The basal compartment containing the spermatogonia and preleptotene
spermatocytes is exposed to plasma; however, the adluminal compartment,
which contains primary and secondary spermatocytes, spermatids, and tes-
ticular sperm, prevents these antigens from entering the blood. The inabil-
ity of cryptorchid testes to produce fertile sperm is related to the higher
temperature in the abdomen than in the normal scrotal location (answer c).
247.The answer is b.(Ross and Pawlina, p 787. Young, pp 341, 351–355.
Junqueira, pp 444–451. Kierszenbaum, p 578.)The secretory phase of the
menstrual cycle depends on progesterone secretion and follows the prolif-
erative (follicular) phase. The menstrual phase occurs after the secretory
phase. During the follicular phase (approximately days 4 to 16), estrogen
produced by the ovaries drives cell proliferation in the base of endometrial
glands and the uterine stroma. The proliferative phase culminates with
ovulation. The secretory phase (approximately days 16 to 25) is character-
ized by high progesterone levels from the corpus luteum, a tortuous
appearance of the uterine glands, and apocrine secretion by the gland cells.
During this phase, maximum endometrial thickness occurs. The menstrual
phase (approximately days 26 to 30) is characterized by decreased glandu-
lar secretion and eventual glandular degeneration because of decreased
production of both progesterone and estrogen by the theca lutein cells.
Contraction of coiled arteries and arterioles leads to ischemia and necrosis
of the stratum functionale. The events of the menstrual cycle are shown in
the figure on the next page.
Reproductive Systems Answers 379