The cell cycle during lens regeneration

Abstract

Abstract The cell cycle in the proliferating zone of the lens regenerate of the adult newt, Triturus viridescens , was investigated by autoradiography using H 3 ‐thymidine as the labeled precursor. For estimation of the DNA synthetic period (S period), we followed the changes in frequency of labeled mitoses after injection of the labeled precursor in 15‐day regenerates. The synthetic index of regenerates (number of labeled cells/number of cells in proliferation zone) was measured at 5, 8, 11, 15, 20, 25, and 30 days after lens removal. For 15‐day regenerates, the DNA synthetic period was estimated to be ca. 19 hours, the G‐2 period ca. 2 hours, the G‐1 period ca. 40 hours, and the cell generation time ca. 65 hours. The synthetic index increased with the progress of regeneration. Using the DNA synthetic period found for 15‐day regenerates, we calculated the average generation time for each stage of regeneration. It decreases from 11 days at stage I to 2.5 days at stages X and XI.