Neural tissue formation requires coordinated, interwoven development of both neural and vascular cells. Spatially distinct regions of the central nervous system (CNS) express factors that are predicted to affect vasculature in one area but not another, yet an example of this idea has not been found. Due to its accessibility, the eye is an excellent tissue to study this question. The factor TBX3 is required for frog eye development, yet its role in mammalian eye formation was not known. To determine how Tbx3 loss-of-function affected eye formation, we crossed the validated Tbx3-floxed mice with the optic cup-Cre recombinase driver, BAC-Dkk3-CRE. We confirmed earlier expression studies of Tbx3 RNA and protein in the embryonic dorsal optic vesicle and, postnatally, in sporadic clusters of cells of the inner nuclear layer. Surprisingly, we also found TBX3 in astrocyte precursors at P0. With Tbx3 loss, blood vessels were malformed throughout the retina, but with more severe effects seen in the dorsal retina. Astrocyte precursors were reduced in number and failed to form a lattice at the dorsal edge. We next examined retinal ganglion cells, as they have been shown to play a critical role in retinal angiogenesis. We found that a subset of intrinsically photosensitive retinal ganglion cells (ipRGCs) were missing melanopsin in the dorsal half of the retina. In previous studies, loss of melanopsin has been linked to hyaloid artery persistence, which we also observed in the Tbx3 cKO retina. Together, these results show that TBX3 is required for retinal angiogenesis.Summary StatementTBX3 is a multifunctional protein important for frog eye development. This is the first study showing that TBX3 is critical for mammalian eye formation, controlling the function of key cells required for angiogenesis.