EPITHELIAL-CELL MIGRATION IN THE NORMAL RAT LENS

The purpose of the present study was to estimate the rate of the rat l ens epithelium displacement. Twenty-four adult male rats were injected intraperitoneally with 18.5 kBq/g [H-3] thymidine. Rats in groups of three were killed at the following times: after one hour, 3, 6, 9, 12, 15, 18 and 21 days. The enucleated eyes were fixed in formalin, embed ded in paraffin, cut into 5 mu m-thick sections, and subjected to auto radiography. The number of cells was counted, and the x-coordinate of each nucleus with three grains or more, and its grain content were rec orded. Statistical analysis included analysis of variance and linear r egression. The average lens diameter was 68 fields of 75 mu m each (5. 1 mm). Cell displacement was measured in two regions: Region A, the eq uatorial region, extending from field 0-20, and region B extending fro m field 20 to the lens center (field 34). Cells in region A are divide d into two kinetic compartments, progenitor (P-cells) occupying fields 9-20, and non-proliferating (Q) cells occupying fields 0-8. Cells adv anced from the P into the Q-compartment at a velocity of 21.8 mu m/day . Cells did not move between field 20 and the lens center. These findi ngs resemble kinetically renewing tissues, e.g. epidermis and crypt-vi llus in the gastrointestinal mucosa.