title: Karyomegaly and intranuclear inclusions in the renal tubules of sentinel ICR mice (mus musculus).
abstract: Among 585 sentinel ICR mice (Mus musculus), 8 (7 female, 1 male) had unusual microscopic lesions in the kidney. Light microscopy revealed occasional tubular epithelial cells with large, karyomegalic nuclei that contained intranuclear inclusions and marginated chromatin. These cells were randomly present in the cortex and medulla but were more prominent near the corticomedullary junc tion. Rare pyknotic cells and mild interstitial infiltrates of lymphocytes and plasma cells were associated with occasional foci of abnormal cells. Electron microscopy performed on 2 (1 female, 1 male) of the mice demonstrated intranuclear inclusions composed of abundant flocculent, electron-lucent material. No viral particles or other pathogens were identified. General health monitoring that included serology, microbiology, parasitology, necropsy, and histopathology was negative for pathogens. Polymerase chain reaction-based testing for polyomavirus and immunohistochemistry for adenovirus were performed on 5 of the 7 female mice; all were negative for both viruses. In light of microscopy findings and the lack of evidence for an infectious agent, the tubular lesions were considered degenerative changes, possibly due to a toxic insult. The cause and significance of the findings in these mice can not be explained fully.
authors.affiliation: Michale E Keeling Center for Comparative Medicine and Research, The University of Texas MD Anderson Cancer Center, Bastrop, Texas, USA. wbaze@mdanderson.org
authors.forename: Wallace B
authors.initials: WB
authors.lastname: Baze
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Steinbach
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Fleetwood
authors.forename: Terrell W
authors.initials: TW
authors.lastname: Blanchard
authors.forename: Kirstin F
authors.initials: KF
authors.lastname: Barnhart
authors.forename: Mark J
authors.initials: MJ
authors.lastname: McArthur
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure*; D002843:Chromatin / Q000648:ultrastructure; D005260:Female; D045586:Intranuclear Inclusion Bodies / Q000648:ultrastructure*; D007674:Kidney Diseases / Q000473:pathology / Q000662:veterinary*; D007684:Kidney Tubules / Q000648:ultrastructure* / Q000821:virology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D016133:Polymerase Chain Reaction; D012376:Rodent Diseases / Q000473:pathology*; D018571:Sentinel Surveillance / Q000662:veterinary; D012698:Serologic Tests
chemical_list: D002843:Chromatin