The Glial Cell of Human Cutaneous Sensory Corpuscles: Origin, Characterization, and Putative Roles

Abstract

Sensory corpuscles of human skin are structures located at the peripheral end of the mechanoreceptive neurons and function as low-threshold mechanoreceptors (LTMRs). In its structure, in addition to the axon, there are glial cells, not myelinating, that are organized in different ways according to the morphotype of sensitive corpuscle, forming the so-called laminar cells of Meissner's corpuscles, the laminar cells of the inner core of Pacinian corpuscles, or cells of the inner core in Ruffini's corpuscles. Classically the glial cells of sensory corpuscles have been considered support cells and passive in the process of mechanotransduction. However, the presence of ion channels and synapses-like systems between them and the axon suggests that corpuscular glial cells are actively involved in the transformation of mechanical into electrical impulses. This chapter is an update on the origin, development, cytoarchitecture, and protein profile of glial cells of sensitive corpuscles especially those of human glabrous skin.

Peripheral Mechanobiology of Touch—Studies on Vertebrate Cutaneous Sensory Corpuscles

“…However, there is current evidence that presynaptic components and neurotransmitters are synthesized by non-neuronal cells, and probably released to LTMRs, which, in turn, express the receptors for some of these neurotransmitters. This has been demonstrated in the case of Merkel cell–neurite complexes, and Pacini corpuscles [ 25 , 37 , 141 ], but not for other mechanoreceptors.…”

“…Nevertheless, the discovery that certain ion channels are at the basis of sensitivity, and that mechanical forces can trigger some ion channels (mechanosensitive or mechanically gated ion channels) support that mechanotransduction occurs via those ion channels. Consistently, it is believed that LTMRs innervating the skin [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ] and their cutaneous target cells [ 25 ] display ion channels activated by force or displacement. In other words, gating of ion channels present in cutaneous sensory corpuscles in response to mechanical stimuli is the first step to transduce mechanical energy into electrical activity [ 18 , 20 , 23 , 26 ].…”

Verification and characterisation of human digital Ruffini’s sensory corpuscles

“…They are long fusiform encapsulated structures (0.2-2 mm in length and 50-200 µm in diameter) containing a core formed by a repeatedly branched axon located within collagen bundles (Chambers et al, 1972). As in other types of cutaneous sensory corpuscles (Cobo et al, 2020) LTMRs that detect stretching and tangential forces generated in the skin, as well as the direction of motion of an object (Johnson, 2001;Jones and Smith, 2014;Owens and Lumpkin, 2014;Olson et al, 2016).…”

The Human Cutaneous Sensory Corpuscles: An Update

“…All available data on proteins present in human skin sensory corpuscles were obtained using immunohistochemistry techniques, and references for papers reporting each of those proteins are included in the reviews by Vega’s Lab [ 9 , 10 , 19 , 37 , 38 ] and Pawson et al ( Figure 4 , Figure 6 and Figure 8 ) [ 31 ].…”

“…Thus, deformations in the membrane differ in the cells that form the mechanoreceptors (i.e., axon, glial cells, and endoneurial and/or perineurial fibroblast) and trigger the opening of mechanosensitive ion channels that transduce mechanical energy into electrical activity. The axon of Meissner and Pacinian corpuscles display acid-sensing ion channel 2 (ASIC2), transient receptor potential vanilloid 4 (TRPV4), transient receptor potential canonical 6 (TRPC6), and PIEZO2 immunoreactivity, whereas the inner core of the Pacinian and the lamellar cells of Meissner occasionally show ASIC2 and 4 TRPV4 [ 37 , 38 ].…”