CONVENTIONAL AND HIGH-RESOLUTION SCANNING ELECTRON-MICROSCOPY OF CEREBELLAR PURKINJE-CELLS

The Purkinje cells of teleost fish, primate and human species have bee n studied by means of conventional (CSEM) and high resolution scanning electron microscopy (HRSEM), using the slicing and ethanol-cryofractu ring techniques and freeze-fracture method. The outer surface of Purki nje cell bodies, dendrites and axons were exposed after selective remo val of Bergmann glial cells. A partial view of the pericellular nest a nd infraganglionic plexus was obtained. The freeze-fracture method for CSEM allowed us to visualize the microtrabecular arrangement formed b y endoplasmic reticulum and cytoskeleton. Climbing fibers were observe d crossing the Purkinje cell layer, exhibiting an arborescence type of bifurcation and endings upon the Purkinje cell dendritic spines by me ans of bulbous knobs. The synaptic relationship between Purkinje dendr itic spines and parallel fibers or granule cell axons was also charact erized. Fractured parallel fiber synaptic varicosities exhibited the t hree-dimensional image of spheroidal synaptic vesicles. Examination wi th the field emission HRSEM showed the synaptic Vesicles immersed in a n homogeneous extravesicular material. The SE-E image profile of the s ynaptic membrane complex was collected. The postsynaptic membrane and the associated postsynaptic density showed round subunits, 25-35nm in diameter. By their localization they could correspond to synaptic prot eins or neurotransmitter receptors.