[Quantitative characteristics of ultrastructural changes in axo-dendritic synapses under the influence of tetanus toxin].

Changes in synaptic ultrastructure of the external geniculate body (EGB) were investigated in rats when a generator of pathologically intensified excitation (GPIE) was produced in this nucleus under the influence of tetanus toxin (TT). At the period of pronounced convulsive activity (24 h after TT injection), synaptic changes were estimated electronmicroscopically and with quantitative comparison of the materials from three groups. The first group included EGB synapses where TT was injected, the second group included contralateral EGB synapses and the third included EGB from the rats injected with inactivated toxin. By means of electron optic computer "Klassimat" average amount of round, flat, anomalous and adjacent to the presynaptic membrane vesicles was measured, average relative length of the active zone, average area of the presynaptic terminal, average relative section areas of pre- and postsynaptic cytoplasm condensation were estimated. In the area of GPIE formation, under the influence of TT, the increased amount of the vesicles related to the presynaptic membrane and that of flat vesicles were statistically significant. At the same time, the synaptic terminals, by the number of vesicles, have bimodal, while the control groups have unimodal distribution.