第十三章 生殖
2011-06-08 18:30:32   来源：   作者：  评论：0 点击：

Summary
The physiology of the reproduction is to produce offspring. The process of reproduction includes fertilization, pregnancy and delivery. Reproduction is modulated by the neuroendocrine system of hypothalamus-adenohypophysis-testes axis.
The testes must descend out of the abdomen to function properly. Spermatozoa are produced by mitosis, followed by meiosis, and then followed by spermiogensis. The main hormones of spermatogenesis are LH, testosterone, and FSH, together with several auxillary hormones.
The first half of the ovarian cycle involves follicular development which is estrogen-dominated and is separated by a short ovulatory phase from the progesterone-dominated second half which prepares the uterus for implantation. All of a woman's primary oocytes (2 million) are present at birth; no more are made. The ovarian cycle consists of one of the several follicles developing into a primary follicle, then Graafian follicle, then a corpus luteum under the influences of FSH and LH. Ovulation is triggered by a powerful surge of gonadotrophins.The ovarian cycle is "shadowed" by the menstrual cycle during which the uterine endometrium is firstly proliferative (due to estrogen) then secretory (due to estrogen and progesterone). Decline in progesterone and estrogen when the corpus luteum degenerates precipitates a menstruation.
Human pregnancy lasts 40 weeks, divided into three trimesters. Only 1 per 100,000 sperm of the 200~400 million contained in the 3~4 ml of the ejaculation deposits near the cervix, where capacitation takes place, reach the fallopian tubes where fertilization ideally occurs. Enzymes from the acrosomes of the many sperm digest the intercellular cement between the cumulus cells, allowing a single sperm to penetrate. On penetration by the first sperm, the ovum becomes impervious to other sperm. A second polar body is released. About 6 days after fertilization, the zygote (now a blastocyst) implants. The placenta takes over the production of estrogen and progesterone from the corpus luteum after the first trimester of the pregnancy. Placenta progesterone inhibits inappropriate contractions of the myometrium. Labor is divided into three phase: first－from onset of contractions to full dilatation of the cervix; second－to delivery of the fetus; third－the expulsion of the placenta.
（中山大学中山医学院 周灿权 王庭槐）
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复习参考题
1．男性的生殖功能具有哪两个功能，有什么特点？
2．精子发育成熟要经历哪几个阶段？
3．睾丸能分泌何种激素，简述男性激素的生理功能。
4．睾丸的生精过程受哪些激素调节？
5．简述受精的过程。
6．简述雌激素分泌的双重细胞学说及雌激素分泌的调节。
7. 简述妊娠的生理过程，妊娠的维持和激素调节。
8. 比较睾丸与卵巢功能调节的特点。
9. 运用所学的知识，设计安全避孕的方法并解释其原理。