Three-dimensional analyses of touch domes in the hairy skin of the cat paw reveal morphological substrates for complex sensory processing

The study investigated the three-dimensional morphology of touch domes in the hairy skin of cat forepaws using confocal laser scanning microscopy and transmission electron microscopy. It was found that a 1 cm² area of interdigital skin could contain up to 68 touch domes, each with up to 150 Merkel cells. These cells were innervated by a single large-caliber afferent myelinated nerve fiber, which branched into multiple myelinated and unmyelinated branches, forming Merkel cell–axon complexes. The intricate innervation pattern was suggested to explain the unique irregular discharges of action potentials typical for this type of mechanoreceptor, contributing to complex sensory processing.