[Differences in the cytoskeleton in inhibitory and excitatory synapses].

The cytoskeleton of afferent chemical synapses, with various ultrastructure of contact zones, was examined in the Mauthner cells of the goldfish. The synapses with combined active zones and desmosome-like specialized contacts possessed a well developed cytoskeleton consisting of filaments and microtubules oriented towards the synaptic apposition. Regular arrays of synaptic vesicles oriented in the same direction were observed beyond and near the active zones. The cytoskeleton of the synapses lacking desmosome-like formations was diffusely organized throughout the boutons. The distribution of vesicles in the vicinity of active zones was also not ordered. The role of cytoskeleton in organization of the two morphologically distinct synapses is discussed. A special function of cytoskeleton as an intermediary between synaptoplasm and membrane is regarded as a necessary basis for plasticity of excitatory rather than inhibitory synapses.