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Abstract
Alloxan-diabetic rats demonstrated a striking transient stimulation of cell division in the lens epithelium which was identical in time course to that occurring in galactose-fed rats, although of less magnitude. Under both experimental conditions, the wave of increased mitotic activity was rapid in onset, reached a peak at 4 days, and subsided by 7 days. No signs of cell death or morphological abnormalities accompanied the rise in rate of cell proliferation. Xylose-feeding induced no change in the mitotic activity of this cell population. In the case of galactose, the burst of mitoses coincided with the appearance of typical equatorial opacities and a marked increase in lens volume. Swelling was detected as early as 12 hours and reached a maximum at 4 days. Alloxan diabetic lenses, however, showed, no increase in volume during the period of mitotic stimulation and biomicroscopically visible opacities did not develop until after the wave of proliferative activity had subsided. Additional rat lenses were maintained in vitro so that the galactose-induced osmotic swelling could be controlled by appropriate variation in the tonicity of the medium. A toxic effect of galactose in vitro characterized by mitotic inhibition and severe damage of the epithelial cells prevented the appearance of the proliferative response and the possibility of testing the relation of this response to lens sivelling.