The ultrastructure of encapsulated sensory corpuscles in the fungiform papillae of monkeys.

Both simple and coiled simple encapsulated sensory corpuscles in the fungiform papillae of primate tongues were examined by light and electron microscopy. These were found to be composed of discoid axon terminals, with cytoplasmic lamellae of lamellar cells surrounding them. The axon terminals were characterized by the presence of distinct finger-like projections extending beyond the corpuscular basal lamina to make contact with collagen fibers, as well as numerous mitochondria, clear vesicles and a few dense-core vesicles in the axoplasm. The cytoplasmic lamellae of lamellar cells showed a number of caveolae on the plasma membrane. Further, desmosome-like contacts were found between adjacent lamellae and between the axon and the innermost lamella.