Age-Related Neoplastic and Degenerative Lesions in Aging Male Virgin and Ex-Breeder ACI/segHapBR Rats

Abstract

A variety of neoplastic and degenerative lesions were observed in 216 aged male breeder (to 24 months of age) and virgin ACI/segHapBR rats sacrificed from 24 to 40 months of age. The most common neoplasms were pheochromocytomas, pituitary tumors, interstitial cell tumors of the testis, and tumors of the skin and subcutis. Many rats had multiple endocrine tumors. Age-related prostate hyperplasias and tumors were reported previously in these rats. Most of these tumors increased in incidence with advancing age, with few differences between virgins and ex-breeders. Testicular atrophy and tumors were more common in younger ex-breeder rats than in young virgin rats, but tumors reached a similar incidence in older virgin rats. Focal hyperplastic lesions appeared to represent the earliest stages of neoplasia in pituitary and adrenal glands, thyroid, prostate, testis, and liver. Common age-related nonneoplastic degenerative lesions were found in various tissues.

Proliferative and Nonproliferative Lesions of the Rat and Mouse Respiratory Tract

“…(Beer and Malkinson 1985;Belinsky et al 1992Belinsky et al , 1991Boorman 1985a;Boorman 1985b;Boorman 1985c;Boorman, Morgan, and Uraih 1996;Boorman and Eustis 1990;Branstetter and Moseley 1991;Breeze and Wheeldon 1977;Dungworth, Ernst, et al 1992;Dungworth, Hahn, et al 1992;Dungworth et al 2001;Foley et al 1991;Gunning, Goldblatt, and Stoner, 1992;Heath, Frith, and Wang 1982;Malkinson 1989;Maronpot et al 1991;R. A. Miller and Boorman 1990;Mohr et al 1990;Ohshima et al 1985;Palmer 1985;Palmer and Grammas 1987;Plopper et al 1983;Pour et al 1976;Rehm and Ward 1989;Rehm, Ward, and Sass 1994;Rehm et al 1988;Reznik-Schüller and Reznik 1979;Rittinghausen et al 1992;Rittinghausen et al 1996a;Rittinghausen et al 1996b;Schüller 1987;Schüller 1990;Singh et al 1985;Thaete et al 1987;Malkinson 1990, 1991;Thaete, Nesbitt, and Malkinson 1991;Ward et al 1983;Ward and Rehm 1...…”

“…A. Miller and Boorman 1990;Mohr et al 1990;2006;2006;Nikitin et al 2004;Ohshima et al 1985;Pour et al 1976;Rehm and Ward 1989;Rehm, Ward, and Sass 1994;Rehm et al 1988;44S RENNE ET AL. TOXICOLOGIC PATHOLOGY Reznik-Schüller and Reznik 1982;Rittinghausen et al 1992;Rittinghausen et al 1996a;Rittinghausen et al 1996b;Schüller 1987;Schüller 1990;Singh et al 1985;Thaete et al 1987;Malkinson 1990, 1991;Ward et al 1983;Ward and Rehm 1990;Ward et al 1985;Witschi 1985;Yamamoto et al 1989) Carcinoma, Acinar (Mice Only) ( Figure 116): Terminal Bronchioles, Alveoli Pathogenesis/cell of origin: Acinar carcinomas are believed to originate directly from bronchiolar epithelial (Clara) cells of the terminal airways by malignant transformation, or to arise from Clara cells populating alveolar walls. Some investigators believe that these tumors arise from parenchymal Clara cells that have migrated from bronchioli to the alveolar epithelium, whereas others consider them to arise from metaplasia of alveolar Type II cells.…”

Proliferative and Nonproliferative Lesions of the Rat and Mouse Male Reproductive System

“…Adenocarcinoma of the prostate and seminal vesicle are rare spontaneous tumors in most strains of rat and mouse (Bosland 1987a(Bosland , 1987bShoda et al 1998). They have been observed in some strains, notably in ACI/ segHapBR rats (Oshima et al 1985;Ward et al 1983). Transgenic mouse models of prostate cancer have also been described Maroulakou et al 1994).…”

Urinary System

“…Renal infarcts are most often seen in animals with other concurrent disease. In another series of aging ACI rats a 12 % incidence of renal infarction was reported (Ward et al 1983). Bacteria can colonize on the valve and periodically detach to produce emboli that result in infarction of many organs, including the kidney.…”