Cystogenesis of the ovarian antral follicle of the rat: ultrastructural changes and hormonal profile following the administration of dehydroepiandrosterone.

Abstract

Immature 27-day-old female Sprague-Dawley rats were administered daily subcutaneous injections of dehydroepiandrosterone (DHEA, 5 mg/100 g BW) to induce the formation of ovarian follicular cysts. Groups of rats were killed on days 0, 10, 15, 20, 25, and 30. Ovaries from each group of rats were processed for light and electron microscopy and for follicular or cystic fluid hormone analysis. Normal antral follicle fluid, PMSG-treated preovulatory follicular fluid, and cystic fluids were analyzed for progesterone (P), estrone (E1), estradiol (E2), testosterone (T), delta 4-androstenedione (delta 4-A), 5 alpha-dihydrotestosterone (DHT), luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL). DHEA induced anovulation, acyclicity, and the formation of follicular cysts. In certain antral follicles, there was a dramatic increase in the quantities of smooth endoplasmic reticulum (SER) in the granulosa cells and many mitochondria had tubular cristae. Further depletion of granulosa cell number was associated with intense blebbing of the cytoplasm into the follicle antrum. Formation of the ovarian follicular cyst was completed when the entire cyst was lined by a single layer of transformed granulosa cells in contact via adhering, gap, and tight junctions. These cells had little cytoplasm, mitochondria with lamellar cristae, vast basal and apical bands of microfilaments, and an extensive array of smooth-surfaced endocytotic invaginations on the basal plasma membrane. These endocytotic pits may subsequently form smooth-surfaced vesicles and thereby serve as one mechanism for moving fluid from the ovarian interstitium into the cyst. Theca interna cells were rarely observed in the peripheral regions of the cyst. Abundant smooth muscle cells were located beneath the basement membrane of the epithelial cells comprising the cyst wall. These acquired morphological and physiological features may ensure persistence of the ovarian cyst and thus potentiate a chronic pathological condition. In this study it was also shown that progesterone, estrone, and estradiol as well as androgen concentration increased in the follicle after PMSG treatment. With DHEA treatment, the follicular cystic fluid concentrations of these steroids progressively increased to extremely high levels concurrent with the development of the follicular cysts.(ABSTRACT TRUNCATED AT 400 WORDS)