Watanabe Ii-sei
Institute of Biomedical Sciences, Department of Anatomy, University of São Paulo, Avenue Prof Lineu Prestes, 2415 Cep, 05508-900, São Paulo, SP Brazil.
Anat Sci Int. 2004 Jun;79(2):55-61. doi: 10.1111/j.1447-073x.2004.00067.x.
The present review describes the fine structures of lamellated mechanoreceptive corpuscles, Merkel cell-neurite complexes and free nerve endings in the oral mucosae of mammals, with special attention to axon terminals and lamellar cells. The mechanoreceptive nerve endings of the oral mucosa were studied using histochemistry, immunohistochemistry and transmission electron microscopy techniques. The organized mechanoreceptive corpuscles are present in the mucosae of gingiva, cheek, tongue and soft and hard palate. They are elongated or globular in shape, being located in the connective tissue papillae. The capsule is composed of several layers of cytoplasmic extensions of perineural cells. Numerous bundles of collagen fibers are noted at the periphery of the corpuscle. The lamellated corpuscles are surrounded by several layers of superimposed flattened capsular cell processes. The interlamellar spaces are 0.2-0.4 micron in width and filled with thin fibrillar collagen fibers embedded in the amorphous substance. The lamellar cells contain rich microtubules and are characterized by the presence of caveolae on the surface plasma membrane. The terminal axon contains an abundance of mitochondria and small clear vesicles (20-50 nm in diameter). There are neurofilaments in the center of the axon terminal. Intermediate-type junctions are seen between the adjacent lamellar cells and between the axon and adjacent lamellae. The free nerve endings are found in the subepithelial regions, very close to the basal laminae of mucosal epithelium. They are surrounded by a thin cytoplasm of Schwann cells. Sometimes Schwann cell basal larinae become multilayered. Merkel cells are present within the basal layer of mucosal epithelium and contain characteristic electron-dense granules that are located almost exclusively at the side of cytoplasm in contact with axon terminals. Intermediate-type junctions are noted between axon terminals and Merkel cells.
本综述描述了哺乳动物口腔黏膜中板层状机械感受器小体、梅克尔细胞 - 神经突复合体和游离神经末梢的精细结构，特别关注轴突终末和板层细胞。使用组织化学、免疫组织化学和透射电子显微镜技术研究了口腔黏膜的机械感受神经末梢。有组织的机械感受器小体存在于牙龈、脸颊、舌头以及软硬腭的黏膜中。它们呈细长形或球形，位于结缔组织乳头内。被膜由神经周细胞的几层细胞质延伸物组成。在小体周边可见许多束胶原纤维。板层小体被几层叠加的扁平被膜细胞突起包围。板层间的间隙宽度为0.2 - 0.4微米，充满嵌入无定形物质中的细纤维状胶原纤维。板层细胞含有丰富的微管，其特征是表面质膜上存在小窝。终末轴突含有大量线粒体和小的清亮小泡（直径20 - 50纳米）。轴突终末中央有神经丝。相邻板层细胞之间以及轴突与相邻板层之间可见中间型连接。游离神经末梢见于上皮下区域，非常靠近黏膜上皮的基膜。它们被施万细胞的薄细胞质包围。有时施万细胞基膜会变成多层。梅克尔细胞存在于黏膜上皮的基底层内，含有特征性的电子致密颗粒，这些颗粒几乎只位于与轴突终末接触的细胞质一侧。轴突终末与梅克尔细胞之间可见中间型连接。
