Recent data indicate that the process of neurogenesis in the mammalian central nervous system (CNS) may be regulated by peptide growth factors, such as epidermal growth factor, transforming growth factor-alpha, and acidic or basic fibroblast growth factor. We have investigated whether members of the transforming growth factor-beta (TGF beta) family also play a role in this process and have found that TGF beta-3 is mitogenic for embryonic rat retinal cells in vitro. We also show that TGF beta-3 stimulates production of retinal amacrine cells while photoreceptor production remains unchanged. These data demonstrate that TGF beta-3 can regulate cell proliferation in the CNS during development and can also influence commitment or differentiation, or both, of neural progenitor cells to particular retinal fates.