A stereological study on the nuclear volume of cerebellar granule cells in aging rats.

A morphometric study on age changes of rat cerebellar cortex (Crus I and Crus II) was carried out. The nuclear volume of the granule cells was estimated by means of two unbiased stereological methods: the nucleator, which enabled the estimation of the number-weighted mean volume (VN), and the point-sampled intercepts method, allowing the determination of the volume-weighted mean volume (VV). These parameters enabled the estimation of the coefficient of variation of nuclear volume in the number-weighted distribution [CV(VN)]. All parameters were determined in eight age groups (2, 6, 9, 12, 15, 18, 21, and 24 months--five animals per age) and the mean values of each age group were compared using one-way ANOVA with post hoc comparisons, and regression analysis. It was demonstrated for the first time, using unbiased techniques, that the nucleus of granule cells of the cerebellar cortex showed a significant decrease in its mean volumes (VV) with age, especially from 21 months onwards. Although CV(VN) was not correlated with age, it was also demonstrated that these cells bear a considerable nuclear size pleomorphy that was maintained throughout the age spectrum.