Structural and functional dissection of the Pacinian corpuscle reveals an active role of the inner core in touch detection

Abstract

SummaryPacinian corpuscles are rapidly adapting mechanoreceptor end-organs that detect transient touch and high-frequency vibration. In the prevailing model, these properties are determined by the outer core, which acts as a mechanical filter limiting static and low-frequency stimuli from reaching the afferent terminal—the sole site of touch detection in corpuscles. Here, we determine the detailed 3D architecture of corpuscular components and reveal their contribution to touch detection. We show that the outer core is dispensable for rapid adaptation and frequency tuning. Instead, these properties arise from the inner core, composed of gap junction-coupled lamellar Schwann cells (LSCs) surrounding the afferent terminal. By acting as additional touch sensing structures, LSCs potentiate mechanosensitivity of the terminal, which detects touch via fast-inactivating ion channels. We propose a model in which Pacinian corpuscle function is mediated by an interplay between mechanosensitive LSCs and the afferent terminal in the inner core.HighlightseFIB-SEM reveals detailed 3D architecture of the entire Pacinian (Herbst) corpuscleInner, not outer core mediates rapid adaptation and frequency tuningAfferent terminal detects touch via fast-inactivating ion channelsMechanosensitive lamellar Schwann cells tune afferent terminal sensitivity to touch