Effect of Continuous Gamma Irradiation of the Generation Cycle of the Duodenal Crypt Cells of the Mouse and Rat

Abstract

The mitotic cycle of the rapidly dividing duodenal crypt cells was studied by autoradiography with tritiated thymidine after exposure to continuous [gamma] -irradiation for 12, 35, and 105 days for rats and 12 and 35 days for mice. A well-defined sequence of events occurs: after a 1-day exposure, the movement of cells into or through mitosis is slowed and possibly partially blocked in G2 [2nd generation]; by 12 days, the shape of the curve is normal, but the generation cycle is approximately 20% shorter; the reduction in GT [generation time] duration is temporary, and the GT is approaching control values by 35 days in the mouse and by 105 days in the rat. This reduction in the GT appears to be a compensatory reaction to assist in the production of a sufficient number of cells that replace those damaged by irradiation and hence to maintain the mucosal cover of the villi. The cell damage in the rat''s crypts was different from that in the mice. In the rat, cell damage was evident in the upper part of some crypts.