The regulation of cellular proliferation and differentiation is integral to the formation of tissues and structures in all multicellular organisms. The mechanisms and cellular processes that regulate proliferation and fate specification, when aberrant, are intimately tied to oncogenesis making them highly relevant biological issues. Many questions remain unanswered as to the mechanisms whereby progenitor populations are maintained throughout development, how progenitor cells are triggered to exit the cell cycle with spatial and temporal precision and what signals or cues direct them to differentiate as specific cell types. Experiments described in this grant aim to elucidate these processes and will focus on the neural retina. Specifically, the grant has three aims; 1) to determine if asymmetric cell divisions are involved in vertebrate retinogenesis and to identify the molecular mechanisms that regulate the plane of retinoblast cell division, 2) to determine if cell fate determinants are distributed asymmetrically during retinogenesis and what roles such determinants play in cell fate choices in the retina and 3) to utilize chemical screens for compounds that affect proliferation and differentiation in the retina [unreadable] [unreadable]