Ultrastructural and acid phosphatase histochemical analysis of developmental lens abnormalities in rats with X-ray-induced cataract mutation.

Lenses from normal Wistar rats and those from a Wistar strain with X-ray-induced cataract mutation were examined electron microscopically for morphological characterization and acid phosphatase (AcPase) localization. Ocular anlages of 11 through 18 days of gestation were included in the study. A late-separating or persistent lens stalk occasionally was seen in the mutant eyes at 13 days of gestation, but never was observed in eyes of normal animals. The first regular morphological lens abnormality, also observed at 13 days, consisted of an accumulation of unelongated fiber cells (fusiform cells) in the posterior of the mutant lens. Ultrastructurally, these cells contained increased amounts of polyribosomes and coagulated proteins, but lacked the microtubules characteristic of elongated fiber cells. Intercellular AcPase activity appeared in the lens epithelium of both strains of rat beginning at 13 days of gestation, but was sparse in the normal strain. Intercellular reaction product attributable to AcPase activity also was noted in persistent lens stalks. In all ages combined, 66% of the mutant lenses, but only 20% of the normal lenses displayed intercellular activity. The Golgi/GERL complex in the apical regions of the lens epithelial cells of both strains contained AcPase reaction product. Reactive coated vesicles assumed to be primary lysosomes were present in nearby cytoplasm or associated with the Golgi/GERL. It is possible that the elevated amounts of hydrolase activity found in the mutant lenses may play a role in the development of the cataract characteristic of this lens.