The Ultrastructure of the Olfactory Epithelium of the Guinea Pig

Abstract

The olfactory mucosa of the guinea pig was studied by electron microscopy. Threa cell types, namely supporting cells, basal cells, and receptor cells were observed. The characteristic feature of the supporting cells was the abundance of various single-membrane-limited inclusion bodies. Centrioles were observed in the supporting cells, but no cilia. These cells did not totally surround the receptor dendrites, and up to four dendrites could be seen lying side by side. Tight junctions were noted between these adjacent dendrites. Two main types of receptor cells were distinguished according to the length of the dendrite. In the shortest, flask-like receptor cells the dendrite was entirely lacking. In the terminal swellings of the dendrites kinocilia were observed which had a typical basal body, a thicker proximal shaft and a thinner distal shaft. In the tips of the cilia and in the lateral projections numerous small vesicles were found. Shorter cilia without the distal shaft were also usually seen. The presence of these short cilia is taken as indication of the continuous formation of the cilia. The tight junctions are considered to be the sites of the intermittent synchronous activity in the groups of receptors, whereas the ciliary vesicles are regarded as storing the substances necessary for the depolarization of the plasma membrane.