MALIGNANT MELANOCYTIC NEURAL CREST TUMOR IN A YOUNG CHICKEN (GALLUS-DOMESTICUS)

A malignant melanocytic tumor was found in an 8-week-old chicken. The tumor, which was composed of melanocytes, ganglion cells, nerves, and primitive pressure receptors, was examined by light microscopy, transm ission electron microscopy, and immunohistochemistry. Antibodies to ne uron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), a nd S-100 protein variably stained nerves, but melanocytes were only ra rely immunolabelled by NSE antibodies and there was no specific staini ng of these cells for S-100 or GFAP. Ultrastructurally, neoplastic mel anocytes contained melanin within melanosomes and premelanosomes and d id not resemble Schwann cells.