Modified endoplasmic reticulum in taste bud cells of the Japanese monkey.

Type III cells (receptor cells) in taste buds of vallate papillae in the Japanese monkey often have one or more cytoplasmic bodies composed of modified smooth endoplasmic reticulum in the form of concentric smooth-surfaced cisternae, up to 18 in number. The most peripheral cisternae may be in continuity with rough endoplasmic reticulum (RER). Type II cells have dilated RER cisternae that often contain crystalline plates with an axial periodicity that ranges from 17 to 27 nm. These observations show that both type III and type II cells of the Japanese monkey possess the cytoplasmic machinery to carry out several secretory functions.