Figure 3.

Shows the changing pattern in the labelling index in mouse ventral tongue over the first 24 h after a single injection of tritiated thymidine. The labelling index is presented for the basal cells, suprabasal cells and total cells in the epithelium in the upper panel. The lower panel shows the changing number of cells in a mm length of basal layer with time after tritiated thymidine injection. There is a progressive decrease in the basal cell density over the first 16 h, suggesting a circadian related emigration of cells from the basal layer. The lower panel shows the labelling index changes over the first 4 days after tritiated thymidine injection. After the initial rapid increase in labelling index in the first 24 h, there is a more gradual rise over the subsequent 2 days and a fall off on the fourth day. The mean and standard errors are shown.