Morphological study of a hereditary rat cataract.

Lenses of ICR/f stain rats with hereditary cataract were examined by light and electron microscopy. The earliest change was the frequent occurrence of displaced or migrated nuclei in the posterior sutural area at birth. Unusual dense fibers at the bow area, and swollen fibers in the posterior cortex were observable by just 2 weeks of age. At 4 weeks of age, the appearance of the dense fibers at the bow area became more frequent, and the lenticular nucleus was formed at the center of the lens. At this time the cellular extensions of the posterior cortical fibers began to be interrupted around the posterior sutural area, which might represent a critical change. Following this change, small amounts of liquid were accumulated at the posterior subcapsular region just behind the bow area by 6 weeks of age. The lenticular nucleus was gradually shifted to a posterior location. Between 10 and 11 weeks of age, increased areas of liquefaction extended into almost all the area of the posterior subcapsular region, and as the posterior suture line separated, the opacification rapidly appeared. This animal model seems to suggest the importance of successive formation in the posterior suture.