Renewal of Cell Population in Palate and Tongue Epithelia of Mice

Abstract

The mitotic index and the generation cycle was determined in 60 day old mice. Over a period of one hundred hours, the mitotic index (MI) appears to rise at 2 hours the MI is 2.9, 2.5 and 1.9; at 100 hours, it was 4.4, 4.1, and 3.5 in the dorsum of the tongue, the palate and the ventral surface of the tongue respectively. This rise in MI was attributed to mitotic arrest caused by tritiated thymidine radiation over 100 hours. The generation cycle was determined by the direct graphic method. Tritiated thymidine labeled mitotic figures were counted and their percentage distribution as a function of time was calculated and a curve prepared. The DNA synthesis time was 8 hours for dorsum of the tongue and hard palate and 8 1/2 hours for the ventral surface of the tongue. The G2 was 20 minutes and the mitotic time, forty minutes for the tongue and the palate. The generation cycle for the palate and dorsum of the tongue was 96 hours; for the ventral surface of the tongue, 98 hours. Evidence points to injury of oral epithelial cells over 100 hours radiation: reduction in the thickness of the epithelium; increased keratinization; fragmentation of nuclear material was evident.