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Abstract
Cell proliferation and displacement were studied autoradiographically in the lens epithelium of young rats injected with H-3-thymidine at 6 days of age and sacrificed at intervals between 1 hour and 3 weeks thereafter. A "proliferative zone" characterized by a high incidence of DNA synthesis (H-3-thymidine incorporation) and mitosis was detected slightly anterior to the equator. Cell generation time was shortest in this zone, and progressively longer toward the anterior pole. Differences in generation time were mainly due to variations in the length of the G1 period of the proliferative cycle, although minor variations in the lengths of the G2 and mitotic periods were also documented. The duration of DNA synthesis was relatively constant (about 101½ hours). Cells produced by mitosis in the proliferative zone were displaced toward the equator, where cell division ceased and further cell specialization was initiated. Differences in the functional activities of the common epithelial cell type in different regions of the lens were attributed to regionally varying cellular microenvironments.