Epithelial mitotic activity during the induction of palatal candidosis in the Wistar rat.

Palatal candidosis was produced in 15 Wistar rats by fitting them with an acrylic appliance that covered the palatal mucosa and simultaneously inoculating this site with Candida albicans 3091 (serotype A). A further 15 rats were fitted with the appliance only. Five animals in each group were killed at 1, 2 and 4 weeks, 4 X 5 h after being injected with vinblastine sulphate, as were 5 normal control animals at the start of the experiment. Palatal mucosa was dissected free, fixed, sectioned and stained prior to counting the number of arrested mitotic figures in the basal epithelial layer and measuring the mean thickness of epithelium. The results were expressed as the number of mitotic figures per 1000 basal cells, per unit length of basement membrane and per square millimetre of epithelial surface. After an initial reduction in thickness, the palatal epithelium in both experimental groups became thicker than that of normal control animals, more markedly so in the animals infected with Candida albicans. Similar patterns of mitotic activity were found regardless of the reference unit used as a basis for the calculations. An initial decrease in both experimental groups was followed by a sharp and significant rise, again being more marked in the animals infected with Candida albicans.