Influence of cage shelf level on retinal atrophy in mice (1982)

Greenman, D. L., Bryant, P., Kodell, R. L. et al.

Abstract

The correlation between cage shelf level andretinal atrophywas examined by analyzing data obtained from a chronic study carried out in 24,192 female BALB/cmice. Each cage ofanimalswas maintained on a cage rack at a given shelf level throughout the course of the experiment, thus allowing analysis of data by shelf level.Retinal atrophywas first observed in amousekilled at 12 months but subsequently was observed only at and after 16 months. This lesion was confined largely toanimalson the top shelf. At 24 months, 19.7% of themiceon the top shelf hadretinal atrophywhile 0.2% ofanimalson all other shelves had the lesion. By 33 months,retinal atrophywas present in 30.2% of themiceon the top shelf, 12.0% on the next shelf, and 0.7% on the lower shelves. Differences in retinal morphology were probably caused by differences in lighting intensity. It was concluded that cage shelf level should be considered as an important factor in any chronic studies withmice.