Maximum function of corpus luteum occurs:
Correct Answer: 8-9 days after ovulation
Description: Ans. is d, i.e. 8-9 days after ovulationRef: Shaw 14th/ed, p28Corpus luteum: After ovulation, the ruptured Graafian follicle develops into corpus luteum.* Corpus luteum reaches it maximum maturity by 22nd day of cycle (Size =2cms or more), ovulation occurs on day 14, i.e. 8thdays after ovulation corpus luteum reaches its maximum maturity.* Colour of corpus luteum in early stages is greyish yellow due to presence of lipids and later is distinctive yellow due to pigment carotene.Q* Corpus luteum secretes:a. Progesterone (mainly)b. Estrogenc. Inhibind. Relaxin - secreted by corpus luteum of pregnancy* In non-pregnant states activity of corpus luteui is maintained by hormone LH whereas in pregnant states by hormone hCGQ* The corpus luteum rapidly declines 9-11 days after ovulation and starts forming corpus albicans if pregnancy does not occur* In the first half of the secretory phase, acid phosphatase and potent lytic enzymes are confined to lysosomes. Their release is inhibited by progesterone stabilization of the lysosomal membranes. With the involution of corpus luteum levels of estrogen and progesterone fall, the lysosomal membranes are not maintained and enzymes are released which cause apoptosis of the endometrial cells.* "The withdrawal of estrogen and progesterone initiates important endometrial events, vasoconstriction, the process of apoptosis, tissue loss and finally menstruation" - Leon Speroff 7th/ed, p121* If pregnancy occurs, hCG similar to LH stimulates corpus luteum to secrete progesterone. It's growth reaches a peak at 8th week of gestation and it remains functionally active till 10-12 weeks of gestation, whereby the placenta takes over its function of producing progesterone.
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Gynaecology & Obstetrics
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