A Golgi study of the proximal portion of the human Purkinje cell axon.

The proximal portion of the Purkinje cell axon in normal cerebellum was investigated using the Golgi-Cox method. The axon emerging from the axon hillock tapered as it proceeded distally along the initial segment. The most distal portion of the initial segment was the narrowest (about 1 micron). Then the axon became thicker again in the probable myelinated portion. The length of the axon hillock plus the initial segment ranged from 21 micron to 52 micron, 35 +/- 6 micron on average +/- SD. The axon arose from any site of the soma and the primary dendrite of the Purkinje cell. Almost half of the axons emanated from a lateral surface of the soma. The dendritic arbores of the Purkinje cell with a torpedo were atrophic.