T Okano1, S Uga, S Ishikawa, A Hara, S Shumiya. 1. Department of Ophthalmology, School of Medicine, Kitasato University, Sagamihara, Kanagawa, Japan.
Abstract
PURPOSE: To conduct a long-term observation study of SCR rats that had developed a mature cataract at 11 weeks of age at 3-month intervals until the rats were 12 months old. METHODS: Lenses of 15 rats were examined with both light and electron microscopes. RESULTS: At 12 weeks, opacity was observed in the perinuclear zone and the cortical intermediate layer. Liquefaction of the posterior subcapsular area and regression of cortical superficial fibers were also observed at this stage. Epithelial cells at the anterior polar area were multilayered. At 12 months, the lens recovered as a result of the regenerated lens fibers in the intermediate layer and the cortical superficial layer, although the opacity remained in the perinuclear zone. The multilayered cellular structure in the center of the epithelium returned to its original monolayer form. However, the equatorial epithelial cells became vacuolated and swollen with age, showing regression from the bow region. CONCLUSIONS: These results suggest that the decrease of opacity in SCR rats is merely a temporary phenomenon that reflects the differentiating and metabolizing functions of the epithelial cells. With initiation of epithelial regression, the regeneration of the lens fibers ceased, suggesting that further decrease in opacity was no longer possible.
PURPOSE: To conduct a long-term observation study of SCR rats that had developed a mature cataract at 11 weeks of age at 3-month intervals until the rats were 12 months old. METHODS: Lenses of 15 rats were examined with both light and electron microscopes. RESULTS: At 12 weeks, opacity was observed in the perinuclear zone and the cortical intermediate layer. Liquefaction of the posterior subcapsular area and regression of cortical superficial fibers were also observed at this stage. Epithelial cells at the anterior polar area were multilayered. At 12 months, the lens recovered as a result of the regenerated lens fibers in the intermediate layer and the cortical superficial layer, although the opacity remained in the perinuclear zone. The multilayered cellular structure in the center of the epithelium returned to its original monolayer form. However, the equatorial epithelial cells became vacuolated and swollen with age, showing regression from the bow region. CONCLUSIONS: These results suggest that the decrease of opacity in SCR rats is merely a temporary phenomenon that reflects the differentiating and metabolizing functions of the epithelial cells. With initiation of epithelial regression, the regeneration of the lens fibers ceased, suggesting that further decrease in opacity was no longer possible.