[The glioneuronal interrelations in the nervous system of the crayfish]

The glio-neuronal interrelations in the nerves, connective and ganglia were studied in the crayfish Astacus leptodactylus as a representative of invertebrates. The outer membranes of the ganglia, connectives and nerves are formed by specialized cells with morphological features of the loose connective tissue cells. In the ganglia between the outer membrane and the neuropile there is another type of the connective tissue cells--Leydig's 1st type cells. The sheaths of axon bundles in the connectives and neuropile are formed by the bodies and processes of glial cells. Their processes also cover solitary axons. The neuron bodies are surrounded by glial cells forming trophospongium. Axons of greater diameter are surrounded by a greater amount of glial layers. Specific features of the structure of myelin-like neurite sheaths were found. The ratio of the length of the membrane of gliocytes covering the neurite to the length of the neurite circle on sections of motor fibers of the nerve is 1:15.7; of sensory fibers of the nerve--1:2.1; of connective neurites--1:1.9; of axons inside the ganglion--1:0.4; in the neuropile--1:0.01.