Localization of Estrogen Receptor Alpha and Progesterone Receptor B in the Bovine Ovary During the Follicular and Luteal Phase of the Sexual Cycle

Abstract

Summary Ovarian steroid hormones, mainly estrogen and progesterone, play a central role in the regulation of ovarian functions. The biological effects of progesterone (PR) and estrogen (ER) are dependent on the activation of both PR and ER isoforms. In the present study, we studied the cellular distribution and localization of progesterone receptor B (PR-B) and estrogen receptor alpha (ERα) in the bovine ovaries during the follicular and luteal phases of the sexual cycle using immunohistochemical methods. The estrous cycle stage of 23 Holstein bovines was evaluated by gross and histological appearance of ovaries and blood steroid hormone values. Tissue samples from ovaries were fixed in 10% formaldehyde for routine histological processing. ERα immunoreactivity was observed in nuclei of granulosa cells of growing follicles at all stages from primary to mature follicles, epithelial cells of the germinal epithelium, stroma cells, theca cells, corpora lutea cells and cells of the corpora albicantia. Nuclear staining for PR-B was not detected in the granulosa cells in all sizes of follicles, but was positively stained in germinal epithelium cells, stroma cells, corpora albicantia cells and corpora lutea cells. In conclusion, ERα and PR-B immunoreactivity in bovine ovary were not indicate too much difference between the phases of the sexual cycle but have important differences in cell-spesific localization.