Scanning electron microscopy of human cerebellar cortex.

Scanning electron microscopy and cryofracture technique were applied to study neuronal architecture and synaptic connections of the human cerebellum. Samples were processed according to the technique of Humphreys et al. (1975) with minor modifications. The granule cells exhibit unbranched filiform axons and coniform dendritic processes. The latter show typical claw-like endings making "gearing type" synaptic contacts with mossy fiber rosettes. The unattached mossy rosettes appear as solid club-like structures. Some fractographs show individual granule cells, Golgi neurons and glomerular islands. The climbing fibers and their Scheibel's collaterals were also characterized. In the Purkinje layer the surface fracture was produced at the level of the Bergmann glial cells, which are selectively removed, allowing us to visualize the rough surface of Purkinje cells and the supra- and infraganglionic plexuses of basket cell axons which appeared as entangled threads. In the molecular layer the three-dimensional configuration of the Purkinje secondary and tertiary dendritic branches was obtained. The filiform parallel fibers make cruciform synaptic contacts with the Purkinje dendritic spines. The appearance of stellate neuronal somata closely resembled that of the granule cells. The subpial terminals of Bergmann fibers appeared attached to the exterior of the folia forming the rough surfaced external glial limiting membrane.