Fig. 5. Deletion of Kip1 restores proliferation in Chx10-null retinas. (A-C) DAPI stained cross-sections show that Chx10, Kip1 double null retinas are morphologically rescued compared with Chx10 single null retinas at P0. Arrows indicate the neural retina. L, lens. (D) Counts of dissociated cells show that all three genotypes are significantly different from each other in cell number at P0 (^***P<0.0003). (E-G) TUNEL-positive cells on sections from all genotypes were observed with similar spatial distributions, demonstrating that cell death is not significantly different in wild type, Chx10-null and Chx10, Kip1 double null retinas at P0. Note that because the eye is still growing, the Chx10-null retina is not yet as thin at this age as it will be by P19. Some positive cells are indicated with arrows. (H) In each genotype, fewer than 1% of cells were TUNEL positive, with no significant differences between genotypes. (I) A marker of proliferation (PCNA), and three markers of differentiated cells (recoverin, ß-tubulin and neurofilament), are all present in similar percentages of cells in wild type, Chx10-null and Chx10, Kip1 double null retinas. No marker showed significant differences between genotypes. Cell counts were performed at P0. Scale bar: 400 µm in A-C; 50 µm in E-G.

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