STEROID-METABOLISM IN THE CORTEX AND THE MEDULLA OF THE EARLY FETAL BOVINE OVARY

Suspensions of cells obtained from the cortex and the medulla of the o vary of early bovine fetuses of 4-10 cm in crown-rump (C-R) length wer e used for studies of the metabolism of radiolabeled exogenous steroid precursors. Tritiated dehydroepiandrosterone, androstenedione, and te stosterone were employed as precursors and their metabolic products we re evaluated after separation by thin-layer chromatography. The extent of conversion of tritiated dehydroepiandrosterone to androstenedione was higher in cells from medulla than in those from the cortex. Andros tenedione was metabolized mainly to estrone, and the percent of transf ormation was similar in the cortex and the medulla, but the rate of fo rmation of 17beta-estradiol was higher in the medulla than in the cort ex. Furthermore, cells obtained from the cortex and the medulla aromat ized testosterone to 17beta-estradiol at a similar rate. In all cases, the percent of transformation was higher in ovaries from fetuses of 4 .0 cm in C-R length than those from fetuses of 9.0-10.0 cm in C-R leng th. These data suggest that, in the bovine fetal ovary, the activity o f 3beta-hydroxysteroid dehydrogenase/isomerase and 17beta-hydroxystero id dehydrogenase predominates in the medulla, whereas aromatase activi ty is similar in the cortex and the medulla of the early fetal bovine ovary.