NEWLY-HATCHED CHICK OVARIAN CELL SUBPOPULATIONS METABOLIZE DISTINCTIVELY PROGESTIN AND ANDROGEN PRECURSORS

The aim of this study was to characterize the ability of four differen t cell fractions (F1, F2, F3, and F4), isolated from the ovary of newl y hatched chick by means of subsequent metrizamide gradients (0-15%), to metabolize progestins and androgens. The results showed the presenc e of 17 alpha-hydroxylase/C17-20 lyase and 3 beta-hydroxysteroid dehyd rogenase/isomerase (3 beta-HSD) activities in the typical steroidogeni c cells isolated in F1 (d = 1.012 g/ml). Primary oocytes present in F2 (d = 1.037 g/ml) did not show relevant steroid metabolism in the vari ous assays that were carried out. Fractions 3 (d = 1.055 g/ml) and 4 ( d = 1.071 g/ml), which contained a mixture of prefollicular and poorly differentiated epithelial cells, presented both 5 beta-reductase and aromatase activities, whereas 17 beta-HSD activity was mainly located in the cells of fraction 3. It is highly possible that poorly differen tiated epithelial cells of fractions 3 and 4 are responsible for the s teroidogenic activity. We conclude that in newly hatched chick ovary, typical steroidogenic cells metabolize progestins to androgens, and po orly differentiated epithelial cells further aromatize androgens to es trogens. In addition, we suggest the existence of at least two metabol ically distinct poorly differentiated epithelial cell subpopulations, one presenting SP-reductase and aromatase activities and another exhib iting 17 beta-HSD activity. (C) 1995 Academic Press, Inc.