title: Life span and spontaneous tumors incidence of the Wistar Mishima (WM/MsNrs) rat.
abstract: The life spans and spontaneous tumors in a total of 1960 Wistar Mishima (WM/MsNrs) rats, inbred strain, from the 80-130th generations were examined. The average life span (mean +/- SD) was 731 +/- 173 days (n = 1053) in the males and 813 +/- 214 days (n = 907) in the females (p < 0.0001). The average life span of tumor-afflicted females was significantly longer than that of the non-tumor group (p < 0.0001), while no such difference was observed in males. Tumors were observed in 33 males (3.1%) and 246 females (27.1%). In the males, tumors were often observed under the skin (2.2%). Frequencies of tumors in lung and liver, bones and intestine were less than 0.5%. In the females, incidence of mammary tumor was 20.1%, and various organs such as ovaries, uterus, bones, lung, and liver had tumor incidence frequencies of less than 3.5%. It was concluded that WM/MsNrs rats might be suitable for life span and age-related studies because of their characteristics of length of longevity and the low incidence of spontaneous tumors in both sexes.
authors.affiliation: International Space Radiation Laboratory, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-Shi, Chiba 263-8555, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukuda
authors.forename: Haruzo
authors.initials: H
authors.lastname: Iida
mesh_terms: D000818:Animals; D005260:Female; D008017:Life Expectancy; D008297:Male; D009374:Neoplasms, Experimental / Q000145:classification / Q000453:epidemiology*; D051381:Rats; D017208:Rats, Wistar