Cholinesterase activity of lamellated sensory corpuscles in the rat lip

Non-specific cholinesterase (ChE) activity was demonstrated in lamellated sensory corpuscles of the rat lip by light and electron microscopy using Karnovsky and Roots' method. ChE activity was present in the interlamellar spaces between neighbouring lamellae as well as in the peri-axonal space between axon terminals and their adjacent lamellae. Reaction products were also deposited in some caveolae of the lamellar cell plasma membrane, and in the cisternae of the rough endoplasmic reticulum as well as in the nuclear envelope of lamellar cell bodies. No reaction products were detected within the axon terminals. The findings show that the lamellated corpuscles in the rat lip, like other mechanoreceptors, have intense ChE activity which is probably synthesized in lamellar cells and released into the intercellular spaces. That ChE activity is particularly strong in mechanoreceptors composed of lamellar cells suggests that this enzyme would play an important role in function and/or maintenance of such mechanoreceptive corpuscles.