Suazo Iván, Vega José A, García-Mesa Yolanda, García-Piqueras Jorge, García-Suárez Olivia, Cobo Teresa
Grupo SINPOS, Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Spain.
Faculcultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile.
Front Neurosci. 2022 Mar 9;16:790130. doi: 10.3389/fnins.2022.790130. eCollection 2022.
Sensory corpuscles, or cutaneous end-organ complexes, are complex structures localized at the periphery of Aβ-axon terminals from primary sensory neurons that primarily work as low-threshold mechanoreceptors. Structurally, they consist, in addition to the axons, of non-myelinating Schwann-like cells (terminal glial cells) and endoneurial- and perineurial-related cells. The terminal glial cells are the so-called lamellar cells in Meissner and Pacinian corpuscles. Lamellar cells are variably arranged in sensory corpuscles as a "coin stack" in the Meissner corpuscles or as an "onion bulb" in the Pacinian ones. Nevertheless, the origin and protein profile of the lamellar cells in both morphotypes of sensory corpuscles is quite similar, although it differs in the expression of mechano-gated ion channels as well as in the composition of the extracellular matrix between the cells. The lamellar cells have been regarded as supportive cells playing a passive role in the process of genesis of the action potential, i.e., the mechanotransduction process. However, they express ion channels related to the mechano-electric transduction and show a synapse-like mechanism that suggest neurotransmission at the genesis of the electrical action potential. This review updates the current knowledge about the embryonic origin, development modifications, spatial arrangement, ultrastructural characteristics, and protein profile of the lamellar cells of cutaneous end-organ complexes focusing on Meissner and Pacinian morphotypes.
感觉小体，或皮肤终末器官复合体，是位于初级感觉神经元Aβ轴突终末外周的复杂结构，主要作为低阈值机械感受器发挥作用。在结构上，除轴突外，它们还由非髓鞘雪旺样细胞（终末神经胶质细胞）以及与神经内膜和神经束膜相关的细胞组成。终末神经胶质细胞是梅克尔小体和环层小体中所谓的板层细胞。板层细胞在感觉小体中的排列方式各不相同，在梅克尔小体中呈“硬币堆叠”状，在环层小体中呈“洋葱头”状。然而，两种形态类型的感觉小体中板层细胞的起源和蛋白质谱非常相似，尽管它们在机械门控离子通道的表达以及细胞间细胞外基质的组成方面存在差异。板层细胞一直被视为在动作电位产生过程（即机械转导过程）中起被动作用的支持细胞。然而，它们表达与机电转导相关的离子通道，并显示出类似突触的机制，这表明在电动作电位产生时有神经传递。本综述更新了关于皮肤终末器官复合体板层细胞的胚胎起源、发育变化、空间排列、超微结构特征和蛋白质谱的当前知识，重点关注梅克尔和环层形态类型。
