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The Corpus Luteum Secretes Progesterone, Which Is Essential for Pregnancy

The main function of the CL is the secretion of progesterone, which prepares the uterus for the initiation and maintenance of pregnancy.

The CL forms from the wall of the follicle, which is col­lapsed and folded after ovulation.

With rupture of the follicle, there is a breakdown of the tissues that surround the granu­losa, particularly the membrana propria, and hemorrhage into the cavity can occur from vessels in the theca. The folds of tissue that protrude inward into the cavity contain granu­losa and theca cells and, importantly, the vascular system that will support cell growth and differentiation. Although the granulosa cell is the dominant cell of the CL, theca cells also contribute significantly to the composition of the structure. The process that granulosa cells undergo during the change from estrogen to progesterone secretion, Iuteiiiizationi begins with the onset of the preovulatory LH surge and accelerates with ovulation.

In most domestic species, significant production of pro­gesterone by the CL begins within 24 hours of ovulation. In some species, including the dog and primates, small amounts of progesterone are produced during the preovulatory LH surge; in the dog, this is important for the expression of sexual receptivity, which occurs as estrogen levels decline while progesterone levels increase.

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Source: Cunningham J.G., Klein B.G.. Textbook of Veterinary Physiology. Elsevier Health Sciences,2007. — 720 ð.. 2007

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