Ovarian follicles development and atresia during the estrous cycle in adult female albino rats. immunohistochemical, light and scanning electron microscopic study

ABSTRACT

Maturation of ovarian follicles results from a complex interplay between proliferation, development and atresia within tire ovary. It is dependant not only on hormonal control but also on important paracrine and autocrine regulation exerted by local intraovarian factors. Polypeptide factors as insulin like growth factors [IGF] may play role in tire regulation of the development of follicles in animals arid humans. For better understanding the regulatory mechanisms of foilicular development, this work was conducted to characterize pattern of ovarian follicle development and atresia during various stages of the estrous cycle. So, twenty adult female a/intro rats were used and daily vaginal smears were done to determine tire estrous cycle stage. The animals were sacrificed at the appropriate stage and blood samples were collected for measurement of FSH and LH levels then the ovaries were removed and processed for light and scanning electron microscopic examination. Expression of p53 and JGF-l in the follicular cells was done. Marked atretic c/ranges, increased expression of p53 and decreased expression of IGF-I in the follicular cells were main/v detected in the preantral and tire antral follicles proestrous. This was accompanied by 4.7 ng/ml mean level of FSH and 8.5 ng/ml mean level of LH. On the other hand, minimal atretic changes decreased expression of p53 and increased expression of JGF-I were seen mainly in the large antral follicles at estrous. This was accompanied by 6.2 ng/ml mean level of FSH and 12.4 ng/ml mean el of LH. It was concluded that ovarian follicular atresia is an apoptotic mechanism through 53 tired/a/ed pathway Furthermore, sufficient hormonal concentrations of FSH and LH in addition to increased expression of IGF-I in time follicular cells are important for the ovarian follicles to reach the mature stage