The spatiotemporal pattern of Math5 -lineage cells in the developing control and Math5 -null retinas. Retinal sections from the control (top panels) and Math5-null (bottom panels) retinas at indicated developmental stages were immunolabeled with anti-GFP (green) to mark the Math5-lineage cells. (A) The onset of GFP expression starts at E12 in the NBL of the control and Math5-null retinas. (B and C) At E12.5-E13, GFP+ cells are present in the NBL, the newly formed GCL, and the RGC axon bundles (arrow) of the control retina. In the Math5-null retina no GCL neurons or RGC axon bundles are observed and there are significantly more GFP+ cells in the outermost NBL. (D-F) At E13.5-E17.5, compared to GFP+ cells located in the GCL and the outermost NBL of the control retina, GFP+ cells in the Math5-null retina are detected throughout the retina but no visible GFP+ RGC axon bundle are present. Moreover, there is an increase in GFP+ cells in the NBL and a decrease in the GCL. (G) At P0, GFP is expressed in the horizontal-like cells (arrows) in the INL of control and Math5-null retinas. (H and I) At P7 and P28, GFP+ cells are located in three retinal layers. Compared to the control, twice as many GFP+ cells were seen in the ONL in Math5-null retina and a few GFP+ bipolar-like cells (arrow) are present in the INL. (J) Quantification of GFP+ cells in the ONL, INL and the GCL per 350 μm length of adult retinal sections. l, lens. r, retina. NBL, neuroblast layer. Scale bars equal 100 μm in A (applies to A, B), C (applies to C, D, E), F (applies to F), and G (applies to G-I).