The present studies were conducted to establish interactions between transforming growth factor (TGF)-beta and the epidermal growth factor (EGF) family members, TGF alpha and betacellulin (BTC), relative to proliferation and differentiation of granulosa cells in hen ovarian follicles. Results presented demonstrate expression of TGF beta isoforms, plus TGF alpha, BTC, and ErbB receptors in prehierarchal follicles, thus establishing the potential for autocrine/paracrine signaling and cross-talk within granulosa cells at the onset of differentiation. Treatment with TGF alpha or BTC increases levels of TGF beta 1 mRNA in undifferentiated granulosa cells, while the selective inhibitor of mitogen activated protein kinase signaling, U0126, reverses these effects. Moreover, TGF beta 1 attenuates c-myc mRNA expression and granulosa cell proliferation, while TGF alpha blocks both these inhibitory effects. Collectively, these data provide evidence that EGF family ligands regulate both the expression and biological actions of TGF beta 1 in hen granulosa cells, and indicate that the timely interaction of these opposing factors is an important modulator of both granulosa cell proliferation and differentiation. (c) 2005 Elsevier Inc. All rights reserved.