A canine testicular tumor resembling gonadoblastoma.

A tumor of the left testicle resembling a gonadoblastoma was an incidental finding at necropsy in a 15-year-old male Shetland Sheepdog. This neoplasm was characterized by discrete intratubular aggregates of intimately mixed germ cells and smaller cells resembling Sertoli cells. The latter small cells often formed a single cell layer surrounding the margin of eosinophilic, PAS-positive Call-Exner-like bodies. Electron microscopy showed these bodies to be composed of whorled laminae resembling basement membrane.