Fine structure of the septal olfactory organ of Masera and its associated gland in the golden hamster.

Fine structures of the septal olfactory organ of Masera (MO) and its associated gland, a kind of olfactory glands, were examined in the golden hamster in comparison with those of the olfactory epithelium (OE) and vomeronasal organ (VNO) and their associated olfactory glands. Bipolar neurons of the MO were divided into two types according to their apical morphology, one similar to the receptors of the OE and the other to those of the vomeronasal sensory epithelium (VSE). The former was dominant and interpreted as main receptors of the MO. The other was less in number, but also regarded as a kind of olfactory receptors. The ultrastructural features of supporting cells of the MO were similar to those of the OE rather than to those of the VSE, while those of basal cells were almost in common in the OE, VSE and MO. The associated gland of the MO was positive to both PAS and alcian blue as the Bowman's gland of the OE. The fine structure of the associated gland of the MO was also similar to that of Bowman's gland. The present findings on the fine structure of the MO and its associated gland strongly suggest that the MO fulfills an olfactory function similar to that of the OE.