A quantitative cytochemical analysis of large antral follicles in two types of rat polycystic ovaries

Abstract

Ovaries from normal mature rats, rats injected with testosterone propionate (TP), and from aged rats were removed, and large antral follicles examined by quantitative cytochemical techniques in order to analyze possible enzymatic defects that relate to follicular steroidogenesis. The ovaries from the TP-injected and the aged rats were polycystic. Lipid deposition was analyzed in frozen sections stained with Sudan black. A microdensitometer was used to measure delta 5-3 beta-hydroxysteroid dehydrogenase (3 beta OHD) activity and G-6-PD type IH generation in the theca, and in peripheral region, antral region, and corona radiata of large antral follicles. 3 beta OHD is the enzyme that converts pregnenolone to progesterone. Type IH generation is related to the conversion of androstenedione to estradiol. Lipid droplet deposition was comparable in the three types of follicles. Compared to that in normal preovulatory follicles, 3 beta OHD activity was similar in identical regions of large antral follicles in TP-injected rats, but less in the theca and peripheral region of the membrana granulosa of the aged rat. G-6-PD type IH generation was less in the peripheral region of large antral follicles of both TP-injected and aged rats than in preovulatory follicles. Type IH generation was also less in the theca of TP-injected rats than in the theca of normal rats. This study provides evidence that in spite of their normal appearance, large antral follicles in polycystic ovaries are not physiologically sound. Furthermore, the enzymatic disturbance appears to be different in different types of polycystic ovaries.

Thecal and interstitial cells in polycystic ovaries (PCO) in the rat

“…Recent evidence from our laboratory (unpublished) suggests that the macrocyst is the end product of atresia of type I11 large follicular structures Desjardins and Brawer, 1989). This is consistent with evidence from other models of PCO showing disturbances in steroidogenic activity in large, normalappearing antral follicles (Zoller and Axelson, 1986). The microcyst also exhibits features typical of atresia (an attenuated, degenerating membrana granulosa, thecal hypertrophy etc.).…”