NEOPLASTIC AND NONNEOPLASTIC LESIONS IN AGING F344 RATS

Neoplastic and nonneoplastic lesions in untreated F344 rats used as controls in carcinogenesis tests were tabulated and evaluated. The most common neoplasms in 1794 male rats were testicular interstitial cell tumors, leukemias, pituitary adenomas, and adrenal pheochromocytomas. In 1754 female rats, common tumors were pituitary adenomas, mammamary fibroadenomas, uterine endometrial stromal polyps, and leukemias. A variety of less common and rare tumors were seen in almost every tissue. A few malignant neoplasms were metastatic. Nonneoplastic lesions included nephropathy, cardiomypathy, focal hyperplasias in a variety of tissues, and inflammatory lesions of the uterus. The focal hyperplasias were suggestive of the early stages of neoplasia in lung, liver, pituitary, adrenal, thyroid, and testis. © 1979.