Ovarian biochemical changes associated with chronological aging will be sought as signals of physiological change. Steroid dehydrogenase enzyme activity, in vitro steroidogenesis and also cholesterol metabolism will be measured in Long-Evans rat ovaries. Plasma steroid and prolactin levels will be assessed as well as the ovarian response to gonadotrophin. The influence of neonatal androgen and ovarian aging will be examined. BIBLIOGRAPHIC REFERENCES: Aging and ovarian delta 5-3 beta-hydroxysteroid dehydrogenase in rats. J. H. Leathem and B. H. Shapiro. Proc. Soc. Expt. Biol. Med. 148, 793, 1975. Ageing and ovarian 20 alpha-hydroxysteroid dehydrogenase in the rat. J. H. Leathem and E. D. Albrecht. Submitted to J. Rep. Fert. (8/75).