M. Female Reproductive System -- 1. Nonneoplastic Lesions -- a. Ovaries -- b. Oviduct, Uterus, Cervix, and Vagina -- 2. Neoplastic Lesions -- a. Ovary -- b. Oviduct -- c. Uterine Horns -- d. Cervix and Vagina -- 3. Discussion -- N. Male Reproductive System -- 1. Nonneoplastic Lesions -- a. Testicle and Epididymis -- b. Accessory Sex Glands -- 2. Neoplastic Lesions -- 3. Discussion -- O. Brain -- I. Nonneoplastic Lesions -- a. Vacuolation (Vacuolar Encephalopathy) -- b. Lipofuscin -- c. Basophilic PAS-positive Bodies -- d. Melanosis -- e. Infarcts -- f. Hydrocephalus -- g. Multifocal Spongiform Encephalopathy -- 2. Neoplastic Lesions -- a. Granular Cell Tumors -- b. Glial Tumors -- c. Meningioma -- d. Pineal Gland -- 3. Discussion -- P. Spinal Cord and Nerve Roots -- I. Nonneoplastic Lesions -- 2. Neoplastic Lesions -- 3. Discussion -- Q. Musculoskeletal System -- I. Nonneoplastic Lesions -- 2. Neoplastic Lesions -- 3. Discussion -- R. Skin and Subcutaneous Tissues (Excluding Mammary Tissue) -- I. Nonneoplastic Lesions -- 2. Neoplastic Lesions -- 3. Discussion -- S. Mammary Gland -- I. Nonneoplastic Lesions -- 2. Neoplastic Lesions -- 3. Discussion -- III. General Discussion -- Chapter 5 Evaluation of the Age-associated Risk for Multiple Tumors and Tumor Metastases in Aging Rats -- I. Introduction -- II. Age-associated risk for Multiple Neoplastic Lesions -- III. Age-associated Risk for Malignant Neoplasms to Metastasize -- IV. Discussion -- Chapter 6 Comparisons of the Incidence of Lesions in Rats that Died Spontaneously to Those Killed at Different Ages -- I. Introduction -- II. Comparisons of the Percentage of Selected Lesions in Dead Rats vs. Percentage in the Populationat Risk as Determined by Life Table Calculations -- A. Medullary Thyroid Carcinomas -- B. Pituitary Tumors -- C. Urothelial Tumors -- D. Nonneoplastic Le