Granule cells, mossy fibres and pyramidal neurons: an electron microscopic study of the cat's hippocampal formation, I.

The ultrastructure of mossy fibre terminals, granule cells, and pyramidal neurons was studied in cat material. The average of the mossy terminals and the density of the synaptic vesicles were analysed. The large mossy terminals establish mainly axo-spiny synapses on the apical dendrites of pyramidal neurons in the CA3 area, but some axo-dendritic synapses were also observed. Mossy fibre endings were found in the subgranular layer, and also on the dendrites of interneurons.