| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
The congenital aganglionosis rat (CAGR) develops a congenital mega-intestine. The distal aganglionic segments of the bowel in the CAGR were penetrated by extrinsic nerve fibers. In the dilated region, synaptophysin immunoreactivity (Syn-IR) was almost preserved in all layers of the wall of the intestine. In the constricted distal colon, Syn-IR was scarce in the circular muscle layer (CML) in any histological section. Some Syn-IR was found, restricted to the outermost areas of the circular muscle layer. In the longitudinal muscle layer (LML) of mutant distal colon, loss of Syn-IR was not prominent compared with the great loss of Syn-IR in the CML. Electron microscopical study confirmed that almost no terminals were found in the CML of mutant distal colon. Electron microscopical study confirmed that great loss of terminals was not prominent in the LML of mutant distal colon. Therefore, the CML in any region of a long constricted segment of intestine in the CAGR, is presumed to be an area
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of poor innervation. Present study suggests that poor innervation of the CML is related to the production of constricted segment.
In the inter muscular layer and the LML, some of the exposed nerve terminals made close contact with smooth muscle cells and fibroblast-like cells (FBC). The FBC had a characteristic association with smooth muscle cells. Some of the nerve terminals also seemed to be free nerve endings. In the submucosa, some of the terminals were completely enveloped by Schwann cells, and some seemed to be free nerve endings. In the muscularis mucosae, the exposed nerve terminals were located among the muscle cells. In the lamia propria mucosae, many exposed nerve terminals were closely apposed to subepithelial FBC processes. The subepithelial FBC were stellate with slender branched processes, and completely ensheathed the villus lamina propria. The exposed nerve varicosities containing synaptic vesicles were closely associated with smooth muscle cells of the vascular wall in each layer. Thus, the extrinsic nerve fibers in the distal aganglionic segments of the bowel in CAGR appeared to be targeting the smooth muscle cells of LML, smooth muscle cells of the vascular wall, and FBC. Less
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