IN a previous communication1, it was reported that the incisor teeth of rats kept on a poor South African diet developed signs of deficiency of vitamin A and of calcium. In addition, the sub-enamel tissues contained a large number of macrophages laden with highly refractile orange-coloured granules, as has also been described in vitamin E deficiency by Granados, Mason and Dam2. The present communication records investigations of the granular ameloblasts and macrophages of normal and experimental rats' upper incisor teeth.