[Study of the connections of brain stem respiratory nuclei by the technic of retrograde transport of horseradish peroxidase].

The method of horseradish peroxidase retrograde axonal transport was used to study the connections between neurons of respiratory nuclei and reticular formation of medulla oblongata and descending fibre pathways from these structures in the spinal cord of cats. It is shown that neurons of the nucleus ambiguus and nucleus retroambiguus (the ventral respiratory group) are connected with the ventrolateral part of nucleus tractus solitarius (the dorsal respiratory group) and from direct bilateral connections with each other and with the medial part of medulla oblongata. A wide developed system of direct connections is revealed between the neurons of respiratory nuclei of both parts of the brain stem. A possible role of the studied nuclei is discussed for the rhythmogenesis of breathing and regulation of the respiratory and other motor functions.