Adrenal dysplasia in a young SD rat

The present report describes an adrenal dysplasia in which developmental abnormality was observed in the adrenal gland of a six-week-old male Crl:CD(SD) rat. Microscopically, a localized lesion composed of mildly vacuolated adrenal fasciculata cells with a slightly disturbed cord structure and containing areas with high cell density was observed in a unilateral adrenal gland; no macroscopical changes were detected in the organ. The areas with high cell density consisted of two cell types. One type included small cells with a round nucleus and acidophilic cytoplasm, and the cells were positive for steroidogenic factor-1 (SF-1) but negative for nestin. The other type of cells had a spindle to polygonal shape, clear nucleus, and a cytoplasm with an obscure boundary; the cells were positive for nestin but negative for SF-1, neuronal nuclear antigen, and chromogranin A. These results suggested that the former type of cells were adrenal cortex cells and that the latter were immature neuronal cells. Considering that immature adrenal cortex cells and neural crest cells (future adrenal medulla) are mixed during a stage in rat adrenal gland development, we concluded that the observed lesion was caused by developmental abnormality. To the best of our knowledge, this is the first report to describe dysplasia in rat adrenal glands.