Ultrastructural and carbohydrate histochemical study of the Vater-Pacini corpuscles in the digital pads of the North American raccoon (Procyon lotor), with special regard to basic function

Abstract

Numerous and very large Vater-Pacini corpuscles were observed in the forefoot digital pads of the North American raccoon (Procyon lotor). In addition to ultrastructure, the distribution and selectivity of complex glycoconjugates in this sensory corpuscle type were examined by carbohydrate histochemical techniques, in particular lectin histochemistry. The Vater-Pacini corpuscles present showed the typical lamellar structure known for mammals and contained high amounts of neutral and acidic glycoconjugates with various saccharide residues (α-l-fucose, β-d-galactose, sialic acid) in a specific intracorpuscular distribution pattern, including variations between the outer lamellae and the inner core. The results obtained are discussed with regard to possible functions of the Vater-Pacini corpuscles found in the raccoon forefoot pads. The corpuscular glycoconjugate components may furnish a high and differentiated viscoelasticity for rapid pressure transmission within the large Vater-Pacini corpuscles. Thus, the digital pads of the forepaws can be considered as part of a specific mechanoreceptor system related to excellent object manipulation properties in this mammalian species.