Histological study on regional specificity of the mucosal nerve network in the rat large intestine

Histological study on the reginal difference in the localization of mucosal enteric glial cells and their sheath structure in the rat intestine

“…A recently developed imaging technology called three-dimensional analysis with electron microscopy enables us to easily understand the ultrastructures of animal tissues well. Indeed, using a method for this technology called serial block-face scanning electron microscopy (SBF-SEM), has thus far enabled us to clarify that the micromilieu in the intestinal mucosa differs among regions throughout the intestine [ 2 , 16 , 17 , 18 , 19 , 24 ]. For example, we have clarified that the histological characteristics of fibroblast-like cells, one of the main cell types in the lamina propria, differ among the ileum [ 17 ], the cecum, and the descending colon [ 24 ].…”

“…For example, we have clarified that the histological characteristics of fibroblast-like cells, one of the main cell types in the lamina propria, differ among the ileum [ 17 ], the cecum, and the descending colon [ 24 ]. Moreover, the characteristics of contact between the nerve fibers and various kinds of cells in the intestinal mucosa also are different among the ileum [ 18 ], the cecum, and the descending colon [ 19 ]. However, the regional differences in mEGCs throughout the intestine have not been clarified.…”

“…All procedures performed in studies involving animals were in accordance with the ethical standards of the institution (the Kobe University Animal Experimentation Regulations). We focused on the three different regions, the ileum, the cecum, and the descending colon, in this study because the other types of cells in the mucosa, such as fibroblast-like cells [ 17 , 24 ] and the nerve network [ 18 , 19 ], exhibited the regional differences among these three regions. The data stacks obtained from SBF-SEM in our previous studies [ 17 , 18 , 19 , 24 ] were reused in the present study ( Supplementary Fig.…”

“…Therefore, a sheath structure left incomplete by mEGCs might lead to effective neurotransmission through diffusion. Moreover, in our previous studies, we clarified that the nerve fibers are in contact with more abundant cells in the apical portions of intestinal villi than around the crypt using same data stacks of SBF-SEM [ 18 ], and that the nerve fibers are widely in contact with fibroblast-like cells and macrophages in the luminal side of the cecum [ 19 ]. Thus, the coverage level by mEGCs seems to inversely correlate with the abundance of contact between nerve fibers and various types of cells ( e.g.…”

“…fibroblast-like cells and macrophage) in the lamina propria. Given that the nerve fibers in the luminal side of the rat cecum were frequently in contact with immune cells, especially macrophages [ 19 ], the lack of sheath structure by mEGCs there might contribute to the active regulation of immune cells by the nervous system. These findings suggest that the analysis of sheath structures formed by mEGCs in nerve bundles would be important in order to interpret the neurotransmission manner in the intestinal mucosa.…”