The olfactory and respiratory epithelium in rhesus and squirrel monkeys studied with freeze-fracture technique.

Olfactory and respiratory epithelia was prepared for thin-section and freeze-fracture replicas, and were investigated using electron microscopy. Three cell types were identified in the olfactory epithelium: olfactory receptor neurons (ORN), sustentacular cells (SC) and basal cells (BC); and respiratory epithelial cells (RC) in the surrounding mucosa. ORN and RC were provided with kinocilia. The cilia displayed their characteristic 5-7 rows of proximally situated 'necklaces', seen in freeze-fracture replicas. ORN and SC as well as RC were connected with tight junctions classified as being 'tight', whereas the RC displayed intermediate junctions. No nexuses (gap junctions) were found. It is concluded that the monkey olfactory/respiratory epithelium exhibit the same characteristics as seen in other vertebrates when using thin section/freeze-fracture technique.