[Barrier function of the glia of autonomic axosomatic synapses of the frog]

The electron-microscopic study of the frog sympathetic ganglion revealed two types of axosomatic synapses: commonly known and distant synapses. Two structures of glial muff which are likely to be diffusion barriers, were distinguished. The first barrier is formed by glial processes adjacent to axosomatic synapses. The second one consists of external compact layer of the glial muff. Three types of neuro-glial relations concerning different extent of presynaptic bouton isolation, were described.