Steroidogenesis by avian ovarian cells: effects of luteinizing hormone and substrate availability.

The production of progesterone (P) and estrogen (E) by enzymatically dispersed granulosa and theca cells from chicken preovulatory follicles was examined in 3-h incubations. Accumulation of the P produced by granulosa cells was significantly reduced by the addition of theca cells, whereas E production was increased. The decrease in P accumulation was shown to be due to extensive metabolism of P by theca cells. There were no synergistic effects of luteinizing hormone (LH) and any substrate tested on E production by theca cells. Maturation of granulosa cells was characterized by an increased sensitivity to LH stimulation of P production, but there was no change in pregnenolone conversion to P. Conversely, maturation of theca cells was accompanied by decreased in both sensitivity to LH and the ability to convert substrates to E. The results are discussed in terms of the contribution of each cell type in the production of steroids by chicken follicles during maturation.