[Participation of sacral parasympathetic nucleus in the innervation of the descending colon and the rectum in cats]

The localization and morphometric features of the preganglionic neurons of the spinal sacral parasympathetic nucleus innervating the descending colon and the rectum, were studied in cats, anesthetized with urethane (1.5 g/kg intraperitoneally) using the method of retrograde horseradish peroxidase transport. The solution of the marker was injected under the serosa of the indicated areas of the colon. After 48 h the animals were transcardially perfused with a fixative solution. Frontal sections of the sacral spinal segments were prepared and stained according to M. Mezulam's protocol (1978). It was demonstrated that the indicated areas of the colon were innervated by the neurons of the sacral parasympathetic nucleus, located in SI, SII and SIII segments of the spinal cord. The majority of the labeled cells were observed within SII segment. The neurons of this nucleus, which innervated the indicated areas of the colon, formed two longitudinal groups (lateral and dorsal ones), the cells in which differed by their sizes and longitudinal axis orientation. Most of the labeled cells were detected in the lateral group.