Enzymic Correlates of Physiological Regression of Follicles and Corpora Lutea in Ovaries of Normal Rats¹²

Histochemical changes in the activity of two hydrolytic enzymes (acid phosphatasc and aminopeptidase) considered to be characteristic of lysosomes were studied in ovarian structures. Ovaries from juvenile, adult cyclic, pregnant, lactating, and post-lactating rats were examined. Healthy follicles exhibited almost no detectable enzymic activity. Whenever follicles appeared atretic, marked activity had developed in the follicular epithelium. Comparison of these preparations with sections prepared by routine staining methods suggested that a rise in enzymic activity may be indicative of incipient atresia. Similarly, an increased enzymic activity developed in lutein cells prior to the next ovulation, before shrinkage of the corpora lutea was detectable. The results tend to support the hypothesis that these methods permit recognition of early destructive changes in follicles and corpora lutca, which in both cases may be hormonally determined. Contrariwise, no rise in activity occurred in oocytes of atretic follicles, even when these were undergoing lysis.