STEROID HORMONE FORMATION BY THE RAT OVARY.
ABSTRACT Ovaries were transplanted to the spleens of castrate male rats. After 120 days, slices of ovarian tissue, composed predominantly of corpora lutea, were incubated in Krebs-Ringer bicarbonate medium containing 50 μc acetate-1-14C. Radioactive steroid formation was assessed quantitatively by reverse isotope dilution. The formation of radioactive progesterone and 20α-hydroxy-pregn-4-en-3-one was established. The formation of radioactive 3β-hydroxy-pregn-5-en-20-one, androst-4-ene-3,17-dione, 17-hydroxyprogesterone, testosterone, oestrone and 17β-oestradiol could not be established. It appears that the corpus luteum of the rat, induced by endogenous gonadotrophins, forms only progestins from acetate-1-14C. Contrary to results previously obtained with ovarian tissue transplanted to female rats, radioactive steroid formation in vitro appeared to be augmented by luteinizing hormone (NIH-LH-S1) added to the incubation flasks. Administration of human chorionic gonadotrophin (200 IU/day) for 5 days prior to autopsy did not enhance acetate-1-14C incorporation in vitro.