Inspection of the intact CD1-
PAX77 +/− eyes with a dissecting microscope showed that they all had lens opacities (cataracts). Histologic analysis of 13 CD1-
PAX77 +/− eyes revealed a more severe phenotype than either CBA-
PAX77 +/− or F1-
PAX77 +/− eyes
(Table 1) , which included severe microphthalmia and significant morphologic abnormalities in several eye tissues
(Figs. 2M 2N 2O 2P 2Q 2R 2S 2T) . Corneal diameters were small but not disproportionately so in the smallest CD1-
PAX77 +/− eyes. In all CD1-
PAX77 +/− eyes, the iris was malformed, thicker than both wild-type and CBA-
PAX77 +/− irides, and displayed adhesions and sometimes cystlike cavities (7/13;
Fig. 2N ). The ciliary bodies were disorganized in all eyes, and some had a persistent pupillary membrane
(Figs. 2O 2Q 2R) . CD1-
PAX77 +/− lenses, left in situ for histology, were small and often vacuolated
(Fig. 2S) , and the lens capsule, demonstrated by PAS staining, was thickened, wrinkled (6/13), and adherent to the adjacent tissues
(Fig. 2R) . Densely packed cells with epithelial morphology formed multiple layers beneath the capsule in all CD1-
PAX77 +/− eyes examined (implying subcapsular epithelial cell proliferation;
Fig. 2Q ) and were also sometimes seen between differentiated lens fibers. Retinas showed several abnormalities
(Figs. 2P 2S 2T) ; most were dysplastic (10/13) and contained rosettes (7/13), and some were folded (4/13) and/or adherent to the lens capsule (10/13), but they were still arranged in recognizable layers. Occasional absence of the outer nuclear layer was attributed to homozygosity for a retinal degeneration allele (e.g.,
Pde6b rd1 ) rather the
PAX77 genotype, because it also occurred in some control, wild-type CD1 animals. Sometimes the vitreous cavity was not detectable (3/13), as the retina adhered to the entire posterior lens capsule
(Fig. 2M) . In one of these eyes, the anterior chamber was also absent, because the iris was adherent to the cornea and anterior lens capsule. Less frequently, some CD1-
PAX77 +/− eyes contained an ectopic ball of retinal cells, possibly retinal ganglion cells, between the retina and lens
(Fig. 2T) . The anterior chamber and the vitreous often contained eosinophilic material
(Figs. 2N 2O)similar to that seen in CBA-
PAX77 +/− eyes.