Androgen and Estrogen Synthesis in the Fetal Guinea Pig Gonad12

Abstract

Bisected fetal guinea pig ovaries and testes were examined in vitro for their ability to synthesize androgens from [1-’ CI sodium acetate and estrogens from either I i-� HI androstenedione or 11 ,2-� HI androstenedione. With [1-’ � Cl sodium acetate as the substrate, hexane-soluble steroids, androstenedione and testosterone were synthesized by fetal testes from Day 30 to 65 of development. To a lesser extent, ovaries also synthesized hexane-soluble steroids, but only when ovaries from various stages of gestation were pooled was the synthesis of ‘4C-androstenedione detected. Radioactive testosterone was not detected in ovarian incubations and at no time was 4C-dihydrotestosterone produced by fetal ovaries or testes. More radioactive testosterone and androstenedione (d/min X mg tissue) appeared in Day 30 testicular incubations than in incubations of organs from later stages of development. In addition, between Days 30 and 50 of gestation more testosterone than androstenedione was recovered from the medium, but by Day 60-65 androstenedione predominated. Total activity (d/min X gonad) generally paralleled organ weight and increased with advancing gestation. The rate of 3H20 formation was utilized as an index of 1i-� HI androstenedione aromatization. Ovaries between 30 and 65 days of gestation were considerably more active (d/min X mg tissue or d/min X gonad) in synthesizing 3H20 (2.3-0.3% of the radioactive substrate) than corresponding testes in which activity was not significantly different than that noted for abdominal muscle. When ovaries were incubated with l1,2-� I androstenedione for 60 mm, the rate of synthesis of H2 0, 3H-estrone and 3H-estradiol-17� was constant. In this case tritiated estrogens accounted for 16-23% of the total product radioactivity. The results indicate that fetal guinea pig testes and ovaries contain the necessary enzymes for de novo androgen and estrogen synthesis at a time during development when anatomical and behavioral phenotypes are differentiated.