Histologic changes during selenite cataractogenesis: a light microscopy study.

The purpose of this research was to study the early histologic changes occurring in the lens during the formation of selenite overdose cataract. Fourteen-day-old rat pups received a single injection of 2.25 mg Se (kg body wt)-1. Lenses at each of three stages of cataract formation were observed biomicroscopically, and then 1-2 micron sections of methacrylate-embedded lenses were evaluated with the light microscope. The first observable change was vacuolization, which started at the lens bow and later spread throughout the posterior subcapsular region (Stage 1). This was followed by an abrupt increase in basophilia at the interface between the peripheral nucleus and cortex (Stage 2). Subsequent formation of nuclear opacity was characterized by the presence of opaque particles, abnormal basophilic structures, and lens fiber damage (Stage 3). The data were consistent with the hypothesis that an early site of attack of selenite is at or near the lens bow, and this leads to biochemical changes, fiber cell damage, impaired nutrient circulation, and formation of nuclear cataract.