Gene dose of <i>Pax6</i> regulates dorsal RPE development in an <i>Mitf</i> mutant–lacking MITF protein.

<p>Cryostat sections of eyes of the indicated genotypes and developmental time points were stained with H&E (A–C,G–I,M–O) or labeled for the indicated markers (D–F,J–L,P–R). Note relatively mild RPE thickening in <i>Mitf^mi-vga9/Mitf^mi-vga9</i> (C,F). In contrast, in the presence of one copy of the <i>Pax6^Sey-Neu</i> allele, there is a massive RPE thickening (I,L) as well as staining for the neuronal marker TUJ1 (L). In the presence of the <i>Pax6</i> YAC transgene (O,R), however, no such RPE abnormalities are seen. Arrows point to the thickened RPE (C,F,H,K,I,L) or to the corresponding monolayer RPE in (M–R). Scale bar (A–C,G–I,M–O): 115 µm; (D–F, J–L): 90 µm; (P–R): 60 µm.