Quantitative studies in ageing male and female Chbb:THOM (Wistar) rats. I. Body weight, cerebellar weight and volumes of cerebellar layers.

Body weight, cerebellar weight, and volumes of molecular, granular and medullary layer of the cerebellum of male and female Chbb:THOM (Wist) rats ranging in age from 6 to 34 months were measured. In male rats, peak body weight and cerebellar weight are to be expected in 20- to 22-month-old animals, with a decline of both parameters after this time. In female rats, body weight and cerebellar weight were generally lower and, at variance with male rats, both parameters increased during the whole time of observation. The cerebellar layers exhibited a different rate of volume increase with a marker increase of the medullary layer and a lesser increase of the granular and molecular layer. Thickness and volume of the molecular layer even decreased in both male and female rats after the 19th month. The relative volumes indicated a predominant growth of the hemispheres with advancing age. Our results demonstrate the need for further regional studies in male and female rats. Pros and contras in the use of rodents in geriatric research in comparison with man are discussed.