Postnatal quantitative changes in the cerebellar uvula of albino rats.

The postnatal quantitative changes in cell diameter, cell density and total number of granule cells in the sublobule IXa of female rats from 6 to 760 days old were examined. There occurs and initial rapid increase in cell density from 1232.00 +/- 91.92 granule cells per 10(-3) mm 3 to 2995.50 +/- 322.07 granule cells per 10(-3) mm 3 and from 3 135 316 +/- 233 937 to more than 24 millions of granule cells between the 6th and 25th postnatal day. After the middle of the 3rd postnatal week, cell density and total number of granule cells decrease. The diameter of the granule cells reaches a maximum at the 6th day post partum and decreases continuously with progressing age. The possible mechanisms of these quantitative changes are discussed.