Presented for

ii The development of the retina is a precise balance between intrinsic competence and extrinsic factors. This interplay is known to regulate the generation of cell types in the developing retina and similar mechanisms have been found in other regions of the CNS. In the developing retina, FGFs are a large family of secreted polypeptide growth factors. Fgf15 is the major Fgf expressed during retinal development in mice. Fgf15 is an example of an FGF that has been shown to control proliferation, cell fate specification, differentiation and migration during development. In this thesis I used analysis of specific genes throughout retinal development, as well as characterization of Fgf receptor mutant mice and Fgf15 knockout explant retina. The preliminary data presented evidence that Fgf15 is a good candidate for an extrinsic factor that may regulate retinal progenitor cell proliferation in the developing retina. When combined with the expression data, these findings suggest that in the absence of Fgf signaling