Abstract
The genetic analysis and light microscopic findings on the Congenital Aganglionosis Rat had before reported precisely by Ikadai, H.. This rat shows spontaneously similar symptoms in the bowel to Hirschsprung's disease of human beings. In order to study pathophysiology of this rat, 15 Congenital Aganglionosis Rats were examined on innervation of the bowel by histochemical and electromicroscopic methods besides light microscopy. 5 control siblings were examined by the same methods as control. On histochemical examination, acetylcholinesterase staining method (AChE) and noradrenaline fluorescence used glyoxylic acid were performed to examine the activity on the nerve elements of the bowel. These rats showed long aganglionic bowel (extensive aganglionosis), presenting with many nerve bundles in the submucosa and intermuscular space and a decrease in the propria muscle in the distal aganglionic segment. Also less nerve bundles were observed in all layers in the proxymal aganglionic segment. Nerve fibers in the dilated bowel were similar to those of control rats. AChE activity was observed remarkably in the submucosa and intermuscular space of the distal aganglionic segment. Gradual diminish in AChE activity was observed in the proxymal aganglionic segment. In the muscle layer, AChE activity was observed to decrease or disappear in all aganglionic segment. Noradrenaline fluorescence was less remarkable in the area of the aganglionic bowel than the bowel of control rat. Electromicroscopically, small-sized ganglion celles seen in the transitional zone had no degenerative change. Nerve bundles surrounded by the peririeurium have less collagen fibers than those of human Hirschsprung's disease. These are thought to be extrinsic. Synaptic vesicles had both cholinergic and adrenergic characters. Nerve ending was not found in the propria muscle of the aganglionic segment in our study. Leiomyocyte of this area indicated the pattern of contracted phase. These findings showed that this rat can be used for a proper medel of Hirschsprung's Disease to make clear its pathophysiology. It was suspected that contraction of aganglionic bowel was dependent on denervation of the muscle layer.
