Chicken granulosa cell proliferation and progesterone production in culture: effects of EGF and theca secretions.

Paracrine/autocrine factors like epidermal growth factor (EGF) and transforming growth factor (TGF alpha) produced in the mammalian ovary modulate ovarian functions such as cell proliferation, differentiation, and steroidogenesis. To study similar activities in the avian ovary, we have developed a culture system for chicken granulosa cells using either serum containing or serum-free media. In the defined medium, granulosa cells for the F1, F2, and F3 follicles of the chicken ovary proliferated as indicated by enhanced levels of DNA, synthesised progesterone in similar amounts to those observed in acute experiments, and responded to luteinizing hormone (LH) during and after the culture period. The morphology of the cells and profile of growth in both media (although better in serum than in serum-free medium) are similar to those reported for mammalian cells. EGF stimulated granulosa cell proliferation over 72 hr in culture while inhibiting basal and LH-stimulated progesterone production; these effects were greatest in the less mature cells taken from the F3 follicles. Theca-conditioned medium (TCM) from chicken ovarian theca cell cultures mimicked the effects of EGF when cultured with granulosa cells. Taken together, these results suggest that EGF/TGF alpha-like peptides have a role in avian ovarian function. Moreover, the effects observed for TCM suggest that these peptides may be present in the theca layer with a paracrine function in the adjacent granulosa.