RPC markers are expanded in central retina despite smaller eyes and fewer cells in cey mutants The eyes of cey mutants are smaller than wild-type eyes by 3 dpf in the medial/lateral, anterior/posterior and dorsal/ventral axes (A). This difference is maintained at all time points (A). In addition, the number of cells in each layer is significantly reduced in cey mutants (B), resulting in a reduction of eye size. The number of cells in each layer was estimated by averaging number of TO-PRO-3 stained nuclei in five z-sections 10 μm apart in six different larvae (see the “Materials and methods” section). Retinal stem cell markers are maintained longer in the central retina (black arrowheads) of cey mutants than in wild-types (C–H). vsx2 and notch1a are expressed in the peripheral retina of the wild-type 4 dpf retina (C, G), but are expressed throughout the central (black arrowheads) and peripheral retina in cey (D, H). Cross sections of 4 dpf retinas expressing vsx2 show that vsx2 is expressed in more cells in the CMZ region of mutant retinas (asterisks) and throughout the outer nuclear layer (black arrow E, F). The small eye and expansion of vsx2 expression into the central retina (black arrowheads) is phenocopied in tbl3 morphants at 4 dpf (I, J). The abbreviations in (B) are as follows: ganglion cell layer (GCL), inner nuclear cell layer (INL), outer nuclear cell layer (ONL), photoreceptor layer (PRL). The error bars in (A) and (B) represent the standard error of the mean. Scale bars are130 μm.