Corpus luteum

The concept of hormonal control of ovulation first appeared in 1921 when Ludwig Habedandt, a physiologist at the University of Iimsbmck, showed that extracts of the corpus luteum, containing progesterone [57-83-0] C2 H2q02, could inhibit ovulation and make mice and rabbits infertile (10). Subsequent research showed that this phenomenon occurred in other species as well. 

Another approach to pregnancy termination has been the utilization of progesterone synthesis inhibitors. These compounds block production of progesterone by the corpus luteum and the early placenta. When adrninistered with a prostaglandin, their use can result in medically induced abortions. 

Eier, n.pf. eggs, -albumin, n. egg albumin, ovalbumin, -dotter, m. yolk of eggs, -drtise, /. corpus luteum. -frucht,/. eggplant. gang, m. oviduct, -ol, n. egg-yolk oil, egg oil. -pulver, n. egg powder, custard powder, -schale, /. egg shell, -schalenglanz, m. eggshell luster. Stein, m. odlite, egg stone. 

Progesterone is secreted by the corpus luteum, placenta, and in small amounts by the adrenal cortex. Progesterone and its derivatives (ie, the progestins) transform the proliferative endometrium into a secretory endometrium. Progestins are necessary for the development of the placenta and inhibit the secretion of pituitary gonadotropins, which in turn prevents maturation of the ovarian follicle and ovulation. The synthetic progestins are usually preferred for medical use because of the decreased effectiveness of progesterone when administered orally. 

The ceUular source of the various ovarian steroids has been difficult to unravel, but a transfer of substrates between two cell types is involved. Theca cells are the source of androstenedione and testosterone. These are converted by the aromatase enzyme in granulosa cells to estrone and estradiol, respectively. Progesterone, a precursor for all steroid hormones, is produced and secreted by the corpus luteum as an end-product hormone because these cells do not contain the enzymes necessary to convert progesterone ro other steroid hormones (Figure 42-8). 

A normal ovulatory cycle consists of follicular development, ovulation, corpus luteum development, and luteolysis. 

Corpus luteum The small yellow endocrine structure that develops within a ruptured ovarian follicle and secretes progesterone and estrogen. 

Luteolysis The structural and functional degradation of the corpus luteum that occurs at the end of the luteal phase in the absence of pregnancy caused by the hormones prostaglandin-2(X and oxytocin. Communication between the corpus luteum and uterine endometrium is necessary for luteolysis. 

Rupture of follicle and ovulation secretion of estrogen and progesterone from corpus luteum... 

Young, J.L. (1979) The effect of dimethyl 3,3 -dithiobispropionimidate on the adenylate cyclase activity of bovine corpus luteum. FEBS Lett. 104, 294-296. 

Terranova, P. 1997. Potential roles of tumor necrosis factor-alpha in follicular development, ovulation and the life-span of the corpus luteum. Domestic Animal Endocrinology 14(1), 1-15. 

In females, menotrophins and hCG are used for the treatment of anovulatory infertility. This condition is due to insufficient endogenous gonadotrophin production. Menotrophin is administered to stimulate follicular maturation, with subsequent administration of hCG to promote ovulation and corpus luteum formation. Mating at this point should lead to fertilization. 

After ovulation, the remaining luteinized follicles become the corpus luteum, which synthesizes androgen, estrogen, and progesterone (Fig. 30-1). 

Stormshak, F., Zelinski-Wooten, M.B. and Abdelgadir, S.E. (1987) Comparative aspects of the regulation of corpus luteum function in various species. Adv. Exp. Med. Biol. 219, 327-360. 

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