EFFECTS OF UV-B ON THE GROWTH-PATTERN OF BOVINE PASSAGE-I AND PASSAGE-II LENS EPITHELIAL-CELLS IN-VITRO

To further evaluate the pivotal role of epithelial cell proliferation in lens homeostasis, this study compares the principles of regional gr owth control in central and preequatorial bovine lens epithelial cells in culture. Central lens epithelial cells do not proliferate in vivo while preequatorial cells do. In tissue culture, both central and pree quatorial cells proliferate, albeit at different rates. At all stages investigated, nonirradiated passage I central cells proliferated less extensively when compared to the preequatorial cells. In contrast, cen tral passage II cells showed a higher proliferation rate than peripher al cells until day 7, when the situation reversed. UV-B radiation led to a dose-dependent reduction of cell proliferation but did not change the principle cytokinetic differences between central and peripheral cells in passage I cells. Under all circumstances, passage I cells gre w more intensively than their passage II counterparts. Data on origin- related differences in cell proliferation of cultured lens epithelial cells suggests growth control features other than just the regionally limited expression of growth factor receptors in the preequatorial ext racellular matrix and cell membranes. Investigations are seen as an im portant step towards a better understanding of the features underlying regional proliferation control and its impairments, at least in lens epithelial cells.