Spontaneous nephroblastoma in Sprague-Dawley rats

Pathological findings were described on nephroblastomas occurrred spontaneously in 3 young Sprague-Dawley rats. One side of kidneys was affected in each animal. Microscopically, the tumors consisted of epithelial elements showing undifferentiated to well-differentiated tubular arrangements, sometimes with glomeruloid and glomerular structures. A metastatic tumor nodule was found in the lung of one rat.