The Pacinian Corpuscle

Abstract

The structure of the Pacinian corpuscle was described by Pacini (1835). It is widely distributed in mammals and is similar to the Herbst corpuscles found in birds. The Pacinian corpuscle is an ovoid structure about 1 mm in length and is easily seen by the naked eye in a number of locations such as the mesentery. On microscopic examination, the lamellar structure of the corpuscle is evident, the lamellae giving an appearance which has been likened to a section through an onion. The corpuscle is innervated by a myelinated sensory axon of medium diameter which terminates within the center of the corpuscle. There it loses its myelin and terminates as an unmyelinated axon. Pacinian corpuscles are highly sensitive mechanoreceptors which respond only to rapid mechanical changes. They are particularly responsive to vibration and appear to subserve the type of sensibility known as vibration sense in man. The corpuscle has been extensively studied as to its morphology, its functional characteristics, and its projection to the central nervous system. The discrete nature and large size of this receptor have made it particularly attractive for the study of receptor mechanisms.