AN IMMUNOELECTRON MICROSCOPIC COMPARISON OF OLFACTORY MARKER PROTEIN LOCALIZATION IN THE SUPRANUCLEAR REGIONS OF THE RAT OLFACTORY EPITHELIUM AND VOMERONASAL ORGAN NEUROEPITHELIUM

Immuno-electron microscopy was used to examine olfactory marker protei n (OMP) ultrastructural localization in the supranuclear regions of th e rat olfactory epithelium (OE) and vomeronasal organ (VNO) neuroepith elium. In the OE, OMP immuno-reaction product was observed within the cytoplasm of olfactory chemoreceptor cell dendrites, vesicles and cili a. Reaction product was absent from olfactory microvillar cells and th eir unique microvillar projections. In the neuroepithelium of the VNO, immuno-reaction product was seen within the dendrites of the chemorec eptor cells, and in the bases of their attached microvilli; the remain ing distal portions of these microvilli were unlabeled. These results demonstrate a difference in the distribution of OMP immunoreactivity o ver the surfaces of the rat OE and VNO. They also show that OMP immuno reactivity does not exist in the rat olfactory microvillar cells.