Fig. 4. RGCs are absent and cone photoreceptors are increased in Math5^-/- mice. (A,B) Neurofilament (160 kDa) is normally expressed by RGCs (arrow in A) and horizontal neurons (arrowhead in A). This marker highlights the loss of RGCs and their axon fibers in Math5 mutants (B). Horizontal cells are unaffected. (C,D) Anti-ß-tubulin (TUJ1) labeling shows the absence of RGCs and an excess of cone photoreceptors in Math5^-/- retinae. RGCs are strongly labeled in the wild-type section (arrow). (E,F) Peanut agglutinin (PNA) stains all cone photoreceptors. Individual cones are visible in the wild-type (arrows in E) but the density of cones is greatly increased in the Math5^-/- mice (F). (G,H) The abundance of S-cones is also increased in Math5 mutants. The arrows in G indicate normal S-cone outer segments. Mutant cones are irregularly arranged in the outer retina (brackets in F and H). In some mutant sections, S-cone outer segments were observed within the ONL (arrows in H), OPL or INL. (I) Histogram comparing the abundance of S-cones in Math5^+/- and Math5^-/- mice as a percentage of total retinal cells. The bars show mean values and standard errors for these two genotypes. The increase in cones in Math5^-/- mice is statistically significant (t_s[] = 2.74, P<0.01). (J) Dissociated retinal cells labeled with S-cone opsin antisera (green) and propidium iodide (red). All retinal sections (A-H) are from P21 mice. gcl, ganglion cell layer; inl, inner nuclear layer; onl, outer nuclear layer. Bars are 100 µm in B; 30 µm in F; 50 µm in J.