Neoplastic lesions were observed in untreated aged Sprague Dawley (SD) rats
throughout their lifespan starting at 5 weeks. Their mean survival times w
ere 89 to 105 weeks of age. The total tumor incidences were 70 to 76. 7% an
d 87 to 95.8% in males and females, respectively. The common neoplasmas wer
e pituitary adenoma and adrenal pheochromocytoma in both sexes, testicular
Leydig cell tumor in males and mammary gland tumors, thyroidal C-cell adeno
ma and uterine stromal polyp in females.