The Pathology of Aging 129S6/SvEvTac Mice

Area of Science:

• * Comparative Pathology
• * Genetically Engineered Mouse Models

Background:

• * The 129 mouse strain is widely used for creating genetically engineered mice.
• * Various 129 substrains exist due to genetic drift and outcrossing.
• * Limited data on spontaneous age-related pathology exists for most 129 substrains, except for 129S4/SvJae.

Purpose of the Study:

• * To document the lifespan and spontaneous lesions in the 129S6/SvEvTac mouse substrain.
• * To provide a reference for evaluating phenotypes in genetically engineered mice derived from this substrain.

Main Methods:

• * Longitudinal aging study.
• * Observation of 44 male and 18 female 129S6/SvEvTac mice.
• * Pathological examination for spontaneous lesions and neoplasms.

Main Results:

• * Median survival: 778 days (males) and 770 days (females).
• * Common neoplasms: lung and Harderian gland tumors (both sexes); hepatocellular tumors (males).
• * Common non-neoplastic conditions: blepharoconjunctivitis (both sexes); polyarteritis (males, cause of death); eosinophilic crystalline pneumonia (both sexes, cause of death/comorbidity).
• * Corynebacteria isolated from blepharoconjunctivitis cases, but causality not confirmed.
• * Extrapulmonary epithelial hyalinosis more frequent in females.

Conclusions:

• * This study provides crucial data on the spontaneous age-related pathology of the 129S6/SvEvTac mouse substrain.
• * The findings serve as a valuable reference for researchers using this substrain in genetically engineered mouse models.
• * Understanding baseline pathology is essential for accurate interpretation of experimental results.