Ovarian follicle granulosa cells

Stimulation of ovarian granulosa cells with follicle-stimulating hormone results in the phosphorylation of H3 at Ser-10 [74]. However, neither the Ras-Raf-MEK-ERK signal transduction nor the p38 stress kinase pathways are involved in this response. 

Follicle-stimulating hormone (FSH) induces the Ser-10 phosphorylation of H3 in ovarian granulosa cells by activation of protein kinase A. Based on the response to various protein kinase inhibitors, FSH-stimulated phosphorylation did not involve Rsk2 or MSKl [74]. 

During the follicular phase of the menstrual cycle, one or more follicles are prepared for ovulation. FSH and estrogens are the most important hormones for this developmental process. Complete follicular maturation cannot occur in the absence of LH. Rupture of a mature follicle follows the midcycle peak of LH and FSH by about 24 hours. In humans, usually one mature ovum is released per cycle. During the luteal phase of the menstrual cycle and under the influence of LH, the ovarian granulosa cells of the corpus luteum become vacuolated and accumulate a yellow pigment called lutein. 

The maternal ovaries are removed and examined at the time of necropsy and corpora lutea are counted. The corpus luteum (CL) is a transitory endocrine organ formed from the thecal and granulosa cells of the postovulatory follicle... Information on the number of copora lutea is useful in the interpretation of data on the viability of conceptuses (see below, pre-implantation loss). Corpora lutea counts can be conducted with fresh or fixed tissue, and are generally performed with the aid of a dissecting microscope. Minimal dissection of the ovarian tissue is required (13). 

Ovarian follicles, the basic unit of the ovary, consist of an outer layer of theca interna cells which encircle inner layers of granulosa cells. Granulosa cells, in turn, surround the innermost oocyte-cumulus complex. This complex array of cell layers is essential for the maturation and ovulation of the ovum. Significantly, the granulosa cell, by virtue of its close interaction with the outer theca and inner oocyte-cumulus compartment, serves to integrate information necessary for the achievement of successful follicular development. 

During the follicular phase, the ovarian follicle (preantral follicle) grows by pronounced proliferation of granulosa cells. During the second half of the follicular phase, the follicle accumulates fluid, which leads to formation of an antrum (antral follicle). 

Salvador, L.M., Park, Y., Cottom, J., Maizels, E.T., Jones, J.C., Schillace, R.V., Carr, D.W., Cheung, P., Allis, C.D., Jameson, J.L., Hunzicker-Dunn, M. 2001. Follicle-stimulating hormone stimulates protein kinase A-mediated histone H3 phosphorylation and acetylation leading to select gene activation in ovarian granulosa cells. J. Biol. Chem. 276, 40146-40155. 

G18. Gottschall, P. E., Katsuura, G., and Arimura, A. Interleukin-1 beta is more potent than interleukin-1 alpha in suppressing follicle-stimulating hormone-induced differentiation of ovarian granulosa cells. Biochem. Biophys. Res. Common. 163, 764-770 (1989). 

The involvement of Bcl-2-like proteins in developmental cell death has been extended to other model systems. In granulosa cells of ovarian follicles, apoptosis has been shown to be associated with an increase in box mRNA and a decrease in bcl-Xi mRNA, but without change in bcl-2 expression (Tilly et al., 1995), consistent with the presumed involvement of these proteins in the above-mentioned models. 

The ovarian granulosa cell, in response to stimulation by follicle-stimulating hormone (FSH) from the anterior pituitary gland and through the catalytic activity of P450 aromatase, converts testosterone to estradiol, the predominant and most potent of the ovarian estrogens (see Fig. 34.23). Similarly, androstenedione is converted to estrone in the ovary, although the major site of estrone production from androstenedione occurs in extraovarian tissues, principally skeletal muscle and adipose tissue. 

Oxytocin, Oxytocin is a known stimulator of PGF secretion by the uterus. Moreover, OT-induced labor is due in part to a dramatic increase in the production of PGF, which stimulates uterine contractions (1). Oxytocin was shown to be an activator of PGF release by cultured porcine ovarian follicles (8), and porcine (Fig. 2) and bovine (10 Fig. 1) granulosa cells. Oxytocin also stimulated PGE secretion by porcine ovarian follicles (8 Fig. 3), hamster ovarian cells (9), and bovine granulosa cells (11 Fig. 1). The immunoneutralization of OT produced by porcine granulosa cells inhibited PGE release (10). Thus, OT has been shown to be a stimulator of ovarian PGF and PGE secretion. 

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