[Ultrastructural features of the interneuronal synapses of medical leeches]

The motor area in neuropil of the leech abdominal brain has been studied electron microscopically. Certain data have been obtained on ultrastructural peculiarities in organization of various parts of the dendritic branchings and interneuronal synapses. A weak polarization of chemical synapses, wide distribution of dendro-dendritic connections and increase in number and variability of contacts running from the proximal to distal areas of the neuronal branchings have been noted.