Immunohistochemical Study on Parvalbumin and Calbindin D-28k Immunoreactive Neurons in the Dog Olfactory Bulb

Kim, Jong Joong; Chung, Yoon Young; Phan, Young Soo

Abstract

We have studied the distribution of calcium-binding proteins parvalbumin (PV -IR) and calbindin D-28k (CB -IR) immunoacitivity in the mongrel dog olfactory bulb using monoclonal antibodies and the avidin -biotin -immunoperoxidase method. The possible coexistence of both markers was determined by segmental histochemical and immunohistochemical double labelling of the same section. In the olfactory bulb of mongrel dog, PV-IR and CB-IR were mainly located in the external plexiform layer, and a few scattered in the glomerular layer, mitral cell layer, and glanule cell layer in the order of thier existence. In addition, three neuronal types were observed in the glomerular layer and external plexiform layer border. Horizontal cells and vertical cells of Cajal were also observed after both PV-IR and CB-IR labeling. Distict groups of PV-IR and CB-IR, differing in size, shape, dendritic branching pattern, and staining intensity, were distinguished in the all layers of the olfactory bulb. Specific neuronal populations were positive for both PV-IR and CB-IR markes. No cell colocalized both stains in the mongrel dog olfactory bulb. The number of PV-IR were more than abundant in olfactory bulb compared to the CB-IR cells. The PV-IR and CB-IR postitive cell somata were round, oval, spindle and polygonal in shape, and they were unipolar, bipolar and multipolar in type. The diameters of the somata of the PV-IR and CB-IR neurons were 20~40 micro meter, respectively. Also dendrites of the these neurons were densely arrayed in arborization.