Axon types of prevertebral ganglia and the peripheral autonomic reflex arc

Prevertebral ganglia of cats and rats were studied by means of electron microscopy. Ganglia from control unoperated animals were compared with others following experimental interruptions of postganglionic and preganglionic afferent pathways. Elaborate interconnections were found between peripheral ganglia and visceral organs forming peripherally closed neuronal circuits. Three types of axons were distinguished as main constituents. On this morphological basis the existence of two kinds of peripheral reflex arcs has been postulated.