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Hyperactivity of theca cells causes hyperandrogenism, and hypoactivity leads to a lack of estrogen. [5] Granulosa cell tumors, while rare (less than 5% of ovarian cancers), may both granulosa cells and theca cells. [6] Thecomas are benign proliferations of theca cells that may present with hormonal dysfunction. [7]
Cell culture of granulosa cells can be performed in vitro. Plating density (number of cells per volume of culture medium) plays a critical role for the differentiation. A lower plating density makes granulosa cells exhibit estrogen production, while a higher plating density makes them appear as progesterone producing theca lutein cells. [12]
Theca interna cells express receptors for luteinizing hormone (LH) to produce androstenedione, which via a few steps, gives the granulosa the precursor for estrogen manufacturing. [ 1 ] After rupture of the mature ovarian follicle , the theca interna cells differentiate into the theca lutein cells of the corpus luteum .
The granulosa lutein cells do have aromatase, and use it to produce estrogens, using the androgens previously synthesized by the theca lutein cells, as the granulosa lutein cells in themselves do not have the 17α-hydroxylase or 17,20 lyase to produce androgens. [5] Once the corpus luteum regresses the remnant is known as corpus albicans. [12]
Each type of cell behaves differently in response to FSH. Theca interna cells express receptors for luteinizing hormone . LH induces the production of androgens by the theca cells, most notably androstendione, which are aromatized by granulosa cells to produce estrogens, primarily estradiol. Consequently, estrogen levels begin to rise.
The theca cells form mainly the androgens androstenedione and testosterone. These hormones may then be converted by aromatase in the granulosa cells into estrogens, including estradiol. The corpus luteum normally grows to about 1.5 centimeters in diameter, reaching this stage of development 7 to 8 days after ovulation.
Theca lutein cyst is a type of bilateral functional ovarian cyst filled with clear, straw-colored fluid. These cysts result from exaggerated physiological stimulation (hyperreactio luteinalis) due to elevated levels of beta- human chorionic gonadotropin (beta-hCG) or hypersensitivity to beta-hCG.
The theca externa is the outer layer of the theca folliculi. It is derived from connective tissue, the cells resembling fibroblasts , and contains abundant collagen . [ 1 ] During ovulation, the surge in luteinizing hormone increases cAMP which increases progesterone and PGF2α production.