Abstract
Progesterone plays an important role in the reproductive function and follicular development in mammals. The aim of the present study was to examine the localization of progesterone receptor alpha (PRA) in ovary of pseudopregnant rabbit by immunohistochemical methods. Samples were collected from 14 h. to 18 days of pseudopregnancy. At the first stage of pseudopregnancy (14 h.), the rabbit ovary showed moderate immunostaining of PRA in the granulosa cells and theca interna cells of preovulatory follicle and in the stroma cells. At the middle stage of pseudopregnancy (3-7 days), the rabbit ovary showed strong immunostaining of PRA in ovarian surface epithelial cells, follicular cells of the primary follicle, granulosa cells and theca interna cells of the growing and antral follicles. Moderate immunoexpression of PRA were observed in the large lutein cells and endothelial cells of the corpus haemorrhagicum and corpus luteum and in the stroma cells. At the end of pseudopregnancy (18 days) strong PRA reactions were detected in the small lutein cells of the regressed corpus luteum. Moderate to strong PRA immuno-expression were observed in the proliferated theca interna cells of the atretic antral follicles. The atretic large lutein cells of the regressed corpus luteum showed negative immunostaining for PRA. This study showed that the PRA positive small lutein cells of the regressed corpus luteum and the PRA positive proliferated theca interna cells of the atretic antral follicles were transformed into PRA positive interstitial gland cells. In conclusion, the present study had described the distribution of PRA in the ovary of pseudopregnant rabbit, which is not discussed before in the available literature. It also gives more information about follicular dynamic, formation and origin of interstitial glands, mechanism of ovulation, formation and regression of the corpus luteum.
Highlights
Progesterone (P4) is a steroid hormone that plays an important role in female reproductive activity in vertebrates such as regulation of follicular development, growth and differentiation of ovarian structures, ovulation and luteinization
Weak to moderate reaction of progesterone receptor alpha (PRA) were observed in cytoplasm of oocytes of the primordial follicles (Fig. 1 C), in the interstitial gland cells (Fig. 1A), in the stromal cells (Figs. 1C and D), granulosa cells and theca interna cells of preovulatory follicle (Fig. 1E)
Stigma in rabbit contained weak to moderate PRA immunostaining in the ovarian surface epithelial cells, macrophage, neutrophils, fibroblasts, intermingled granulosa cells and theca interna cells and in the mitotic figure of endothelial cells
Summary
Progesterone (P4) is a steroid hormone that plays an important role in female reproductive activity in vertebrates such as regulation of follicular development, growth and differentiation of ovarian structures, ovulation and luteinization. It participates in maintenance of pregnancy and breast development (Spencer and Bazer, 2002; Conneely et al, 2003; Anzaldua Arce et al, 2010). In our previous study (Abd-Elkareem, 2017a) we demonstrated the localization of PRA in rabbit ovary during pregnancy up to 10 days after pregnancy. We carried out this study to demonstrate the immunolocalization of PRA in the ovary of pseudopregnant rabbit at different periods starting from 14hr to 18 days of pseudopregnancy. In addition to characterize the different levels of PRA expression in rabbit ovaries from 14 h to 18 days
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