Clinical, histologic and scanning electron microscopic study of the development of chronic candidiasis of the rat tongue.

In order to examine the development of the chronic candidal lesion of the dorsal rat tongue, 210 rats were given a single oral inoculum of Candida albicans on Day 0 and were sequentially killed over a 20-wk period. Dorsal tongue changes were evaluated using clinical photographs, histologic sections and scanning electron microscopy (SEM). Clinically evident lesions became apparent at 2 wk post-inoculation, and inflammatory changes of the underlying connective tissue were observed by 3 wk post-inoculation. SEM showed a gradient of destruction of the dorsal tongue papillae at the periphery of the candidal lesions. Hyphae were seen infrequently on the lesional surface by SEM, a finding which correlated with the light microscopy.