Laboratory of Histophysiology, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
Bio 3D Promotion Group, Application Management Department, JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558, Japan.
J Vet Med Sci. 2020 Jul 31;82(7):990-999. doi: 10.1292/jvms.20-0175. Epub 2020 Jun 2.
The comprehensive targets of innervation in the intestinal mucosa are unknown, partly because of the diversity of cell types and the complexity of the neural circuits. Herein, we investigated the comprehensive targets of neural connectivity and analyzed the precise characteristics of their contact structures in the mucosa of rat ileum. We examined target cells of neural connections and the characteristics of their contact structures by serial block-face scanning electron microscopy at four portions of the rat ileal mucosa: the apical and basal portions in the villi, and the lateral and basal portions around/in the crypts. Nerve fibers were in contact with several types of fibroblast-like cells (FBLCs), macrophage-like cells, eosinophils, lymphocyte-like cells, and other types of cells. The nerve fibers almost always ran more inside of lamina propria than subepithelial FBLC, and thus contacts with epithelial cells were very scarce. The contact structures of the nerve fibers were usually contained synaptic vesicle-like structures, and we classified them into patterns based on the number of nerve fiber contacting the target cells at one site, the maximum diameter of the contact structures, and the relationship between nerve fibers and nerve bundles. The contact structures for each type of cells occasionally dug into the cellular bodies of the target cells. We revealed the comprehensive targets of neural connectivity based on the characteristics of contact structures, and identified FBLCs, immunocompetent cells, and eosinophils as the candidate targets for innervation in the rat ileal mucosa.
神经在肠黏膜中的综合作用靶点尚不清楚，部分原因是细胞类型的多样性和神经回路的复杂性。在此，我们研究了神经连接的综合作用靶点，并通过对大鼠回肠黏膜的四个部分（绒毛的顶端和基底部以及隐窝的侧部和基底部）进行连续块面扫描电子显微镜检查，分析了其接触结构的精确特征。我们通过连续块面扫描电子显微镜检查，研究了神经连接的靶细胞及其接触结构的特征。神经纤维与几种成纤维细胞样细胞（FBLC）、巨噬细胞样细胞、嗜酸性粒细胞、淋巴细胞样细胞和其他类型的细胞接触。神经纤维几乎总是比黏膜固有层中的上皮下 FBLC 更靠内走行，因此与上皮细胞的接触非常稀少。神经纤维的接触结构通常包含突触小泡样结构，我们根据一个部位接触靶细胞的神经纤维数量、接触结构的最大直径以及神经纤维与神经束之间的关系，将它们分为不同的模式。对于每种类型的细胞，接触结构偶尔会切入靶细胞的胞体。我们根据接触结构的特征揭示了神经连接的综合作用靶点，并确定 FBLC、免疫活性细胞和嗜酸性粒细胞是大鼠回肠黏膜中神经支配的候选靶细胞。
