THE ROLE OF INTRAMURAL GANGLION CELLS PLAYED FOR REGULATING THE GASTROINTESTINAL MOTILITY

In this review, firstly, the aspects of the normal movements of stomach, small intestine and colon are summarized to be concluded that the movements essentially consist of a kind of the contraction wave. On the basis of the results obtained in the studies on the plexus-containing as well as plexus-free preparations, it is then concluded that acetylcholine released from intramural nervous elements is responsible for maintaining the rhythmic contractions. An evidence has also been presented that the pacemaker is the site, where the intramural nervous elements are distributed much more densely than any other places. Lastly, on the basis of the results obtained recently by Hukuhara and his co-workers the functions of intramural ganglion cells are summarized: The cells consist of excitatory and inhibitory neurones and function as centers of two kinds of intrinsic reflexes; the one is produced by stimulating the mucosa (mucosal intrinsic reflex), while the other by stimulating the muscle coat (muscular intrinsic reflex). The characteristic natures of the reflexes have been described, and evidences that these reflexes play an important role to regulate, on the one hand, the strength and direction of rhythmic contraction waves, and, on the other hand, the transport of contents through the digestive tract, have been presented. When the ganglion cells are completely destroyed, the intrinsic reflexes are completely absolished, and the tone of the muscle remarkably rises. The phenomena are shown to be a primary cause of congenital megacolon and the diseases belonging to the same category. The latter fact, moreover, suggests that in the normal condition the inhibitory neurones persistently discharge to cause a moderate relaxation of the muscle, whereas the excitatory ones are supposed to act only when the mucosa is stimulated.