[Morphofunctional features of the catfish lateral line analyzer]

The peripheral and central portions of the catfish lateral line system were investigated by conventional light microscopical and electrophysiological methods. N. lat. post. X supplying the neuromasts and the small pit organs of the fish body consists of myelinated nerve fibres with the axonal diameters between 2 and 9 mum. The nerve also contains a number of unmyelinated fibres as well as lateral line nerves in other species. Axon conduction velocities were distributed within a range of 10-15 m/s. All afferents pass through the n. lat post. X to the area acoustico-lateralis of the medulla oblongata. Nucleus medialis is associated with the lateral line system. It consists of n. med. p. dors, and n. med. p. med. The former consists of medium size cell bodies (6-14 mum), which are of an oval or triangle shape. The latter consists of small (4-6 mum) oval cells. N. med. p. dors. and n. med. p. med. are the most distinct at the level caudally to the enter of auditory nerve VIII. Rostrally and caudally the both portions of the n. med. overlap each other. Responses to electrical and mechanical stimulation of the lateral line organs were recorded in the entire area acoustico-lateralis. All the neurons under study were situated at a depth of 400-800 mum in the area nucleus medialis.