Structural and functional dissection of Pacinian corpuscle reveals a multicellular mechanism of touch detection independent of the outer core
Lamellated corpuscles are rapidly adapting mechanoreceptors that detect transient touch and high-frequency vibration in many vertebrates. It the prevailing model, these properties are determined by outer core, which acts as a mechanical filter that limits static and low-frequency stimuli from reaching afferent terminal—the sole site of touch detection in corpuscles. Using focused ion beam scanning electron microscopy and single corpuscle electrophysiology, we determine the detailed architecture of corpuscular components and reveal their contribution to touch detection. We show that outer core is dispensable for rapid adaptation and frequency tuning. Instead, these properties are encoded within inner core, composed of gap junction-coupled syncytium formed by lamellar Schwann cells (LCS) around afferent terminal. By acting as additional touch sensors, LSCs potentiate mechanosensitivity of the terminal, which detects touch via fast-inactivating ion channels. Our findings support a model in which lamellated corpuscle function is mediated by a bicellular mechanism within inner core. Overall design: Gene expression analysis and differential transcriptomics of single inner cores of Pacinian corpuscles (n = 7 biological replicates) compared to bill epidermis (n=6 biological replicates) in duck.