Incidence, morphology, and ultrastructure of spontaneous thymoma--the most common neoplasm in W/Nhg rats.
Spontaneous thymoma was observed with an incidence of 97 and 36% in female and male rats, respectively, from an inbred Wistar/Neuherberg strain (W/Nhg). The thymomas often caused dyspnea and were occasionally the direct cause of death. The neoplasms resembled human thymomas and showed a variable cell composition, ranging from mainly lymphocytic to mainly epithelial. The detailed ultrastructural findings are described and compared with those in other rat thymomas and in human thymomas. A characteristic feature of all dividing lymphocytes was the presence of often multilayered, confronting cisternae. As in more than 50% of human thymomas, W/Nhg rat thymomas were not associated with myopathies or any other possibly autoimmune diseases. They may thus offer a useful model for the study of thymoma without associated parathymic syndromes.
D000367:Age Factors; D000818:Animals; D004848:Epithelium / Q000473:pathology; D005260:Female; D008214:Lymphocytes / Q000473:pathology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains / Q000033:anatomy & histology*; D012376:Rodent Diseases / Q000453:epidemiology / Q000473:pathology; D012737:Sex Factors; D013945:Thymoma / Q000453:epidemiology / Q000473:pathology / Q000648:ultrastructure / Q000662:veterinary*; D013953:Thymus Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000648:ultrastructure / Q000662:veterinary*