Computer-assisted analysis of the developing Purkinje neuron. II. A comparative study of the dendritic development in...

Golgi-prepared cerebella from 10-13-(model K) and 22-day-old (model C) kittens were analyzed and compared with 30-40 days in vitro (DIV) horseradish peroxidase (HRP)-stained organotypic cultures from kitten cerebella explanted at comparable ages (12 (model E) and 21 (model T) postnatal days). In addition, HRP-stained cerebella explanted from 1-day-old kittens were used as a reference (model N). Computer reconstructions and morphometric parameters (14 variables) allowed a comparative quantitative analysis of the Purkinje cell dendritic trees and axonal processes. The biplanar arrangement of the dendritic sheets observed in vivo at 10-13 days (K) was replaced by a mostly bipolar one in the in vitro Purkinje cells (E) explanted at the same age with their axon following the direction of either dendrite. The dendritic expansion observed in intact animals between 12 and 22 days was mostly due to an increase in the number of dendritic segments having shorter lengths rather than an increase in the number of rows. A discriminant analysis permitting the recognition of 3 populations of Purkinje cells in both groups reinforced the previous hypothesis that the dendritic shapes are modelled by specific afferents pre-existent in vivo.