Age-related morphometric changes occurring in the somata of astrocytes of the granular layer of rat neocerebellar cortex (Crus I and Crus II).

A quantitative study concerning the age-related changes occurring in the cell body and somatic organelles of neocerebellar astrocytes is carried out, using rats aged 2 to 24 months. Manual stereological techniques are used to determine the following parameters on electron micrographs: the somatic volume, the volume density and the absolute volume of the protoplasmic structures as well as the mean surface of the rough endoplasmic reticulum cisternae per cell. None of the parameters reveals any clear-cut general temporal pattern. The soma and the cell components show statistically significant differences in the parameters with ageing, excepting the dense bodies (relative and absolute volumes) and the Golgi apparatus (relative volume). There are significant positive linear trends between, on the one hand, the somatic volume and, on the other hand, the absolute volume of either of the following structures: nucleus, glial filaments, ground substance and dense bodies. Some linear correlations between the absolute volumes of organelles are also found. Despite the ability for karyokinesis, it is concluded that astrocytes do undergo changes with ageing.