Visualization of crystallin droplets associated with cold cataract formation in young intact rat lens.

The structure, distribution, and nature of scattering elements associated with cold cataract formation in the young rat lens were studied in situ using light and electron microscopy and ImmunoGold electron microscopy. A large accumulation of spherical droplets, ranging from approximately 1.5 microns to 10 microns in diameter, were found in the lens nucleus in cold cataracts induced at 22 degrees C or 4 degrees C in TC-199 culture medium. Many droplets of all sizes were associated with the cell membranes. A cooled and then rewarmed lens was found to lose its opacity and subsequently no droplets were observed, indicating that there was a good correlation between the onset of opacification and the formation of droplets. Electron microscopy showed that droplets were composed of homogeneous electron-dense aggregates without limiting membranes. ImmunoGold study revealed that alpha-, beta-, and gamma-crystallins were all present within each droplet. This study demonstrates that extensive accumulation of the crystallin droplets in the lens nucleus is the contributing factor for the light scattering and opacification of the cold cataract in the young intact rat lens.