Fig. 6. Early stages of RGC and cone formation are abnormal in Math5^-/- retinae. Micrographs of retinal sections from E15.5 (A-F) and E13.5 (G,H) embryos and P0.5 newborn mice (I,J). (A,B) Hematoxylin and Eosin-stained sections of wild-type (A) and Math5^-/- (B) retinae. Mutant retinae are thinner in the radial dimension. Arrows in both panels indicate the position of eosinophilic RGC axon fibers, which are apparent in A but largely absent in B. (C,D) ß-gal expression in Math5^+/- and Math5^-/- retinal sections. Arrows indicate the RGC axon fibers in heterozygotes that are greatly reduced in the mutant. Math5^-/- ß-gal-expressing cells are distributed across the retinal thickness (top to bottom of D). (E,F) Anti-ß-tubulin (TUJ1) immunostaining of E15.5 retinae. A well formed GCL is apparent in the wild-type (E), but is greatly diminished in the Math5^-/- retina (F). (G,H) Neurofilament (160 kDa) immunostaining highlights the failure of Math5^-/- retinae to form a significant number of RGCs at an early stage. Arrows indicate a normal optic nerve in wild-type (G) and abnormal axons in the Math5 mutant that do not exit the eye (H). (I,J) Recoverin immunostaining demonstrates an early increase in the density of cone photoreceptors in Math5^-/- mice (J). on, optic nerve; gcl, ganglion cell layer. Bars are 100 µm in A,E,I; 20 µm in D; and 50 µm in G.