Characterization of dissimilar steroid productions by granulosa, theca interna and theca externa cells during follicular maturation in the turkey (Meleagris gallopavo).

Unlike the established models for steroidogenesis in the rat and human, we have previously demonstrated that in the turkey progesterone (P), androgen (A), and estrodiol (E) are primarily produced by the granulosa, theca interna, and theca externa cells, respectively. In the present study, experiments were conducted to further characterize steroid productions by these cell types during follicular maturation. In Experiments 1 and 2, granulosa cells and theca internal cells, respectively, from the larger (F1) and fifth largest (F5) preovulatory follicles were incubated (1 x 10(5) cells/ml) with ovine luteinizing hormone (oLH) or porcine follicle stimulating hormone (pFSH) for 5 hr. Granulosa production of P from both follicles was stimulated in response to oLH, with both basal and LH-stimulated P production greater in the larger F1 than in the smaller F5 follicle. No A or E production was detected in granulosa cells from either follicle size tested. Theca interna cell productions of P and A were stimulated by oLH in the smaller F5, but not in the larger F1, with both basal and stimulated levels of A greater in F5 than in F1. Medium content of E was non-detectable in cultures of theca interna cells from all follicles tested. In Experiment 3, theca externa cells were incubated (1 x 10(6) cells/ml) from F1 and F5 follicles. The theca interna cells from F5 and the seventh largest follicle (F7) were pooled (1 x 10(5) cells/ml) to provide substrate(s) for theca externa steroidogenesis. Theca externa cells were incubated alone and in combination with the pooled theca interna cells and with or without oLH or pFSH.(ABSTRACT TRUNCATED AT 250 WORDS)