Early cytologic changes of Fraser cataract. An electron microscopic study.

The cataractous lens of the Fraser strain mouse was studied electron microscopically in its early developmental stage. Cytologic abnormalities were found in the cells of the invaginating ectodermal cell of the early optic cup. Morphogenetically degenerating cells were more numerous in this stage. In general, cells of the posterior layer of the developing lens elongated normally. However, they contained great numbers of dilated rough endoplasmic reticulum, vacuoles, and mitochondria, but less amounts of crystalline substance and polysomes. During the further differentiating stage (thirteenth and fourteenth fetal day), apical portions of these cells began to swell and the lens became opaque. The swollen lens cells degenerated after this stage.