Figure 3.

Retraction of Purkinje axon collateral branches during postnatal development. A, Mean number of first-order collateral branches ± SD issued by stem Purkinje axons at different postnatal ages. B, Normalized frequency distribution of the number of collateral branches (br) on individual Purkinje axons during the same period. C, Time course of collateral branch withdrawal in separate samples of Purkinje axons from apical (A), medium(M), or basal (B) regions of corticallobules (indicated by corresponding shadowing on the diagram). The micrographs, all taken from the same cerebellar section at P8, show the nonsynchronous maturation of Purkinje cells located at different basoapical positions along the same cortical lobule (lobule VI). nr, Number.