Fine structure of the receptor-free epithelium in the vomeronasal organ of the rat.

The topography and distribution of the epithelia of the vomeronasal organ were investigated in the adult male rat. Special attention was given to the light and transmission electron microscopic structure of the area that is known to be free of receptor cells. In contrast to several brief descriptions in which many cell types have been reported, only one cell type is presently described in different functional phases. In the rat, this epithelium does not show the typical features of a respiratory or, in more general terms, non-sensory epithelium. The authors propose to call this epithelium as "receptor-free" rather than respiratory, non-sensory or ciliated. The importance of the vomeronasal organ in the maintenance of olfacto-endocrine mechanisms and reproductive behavior is discussed.