| Abstrakt: |
Differential expression of G proteins (Giα2 and Goα) and the separate central projections of Giα2- and Goα-immunoreactive (ir) vomeronasal receptor neurons were investigated in the mouse and rat using immunocytochemical methods. In the vomeronasal organ (VNO), receptor neurons with their cell bodies located in the middle layer (middle 1/3) of the vomeronasal sensory epithelium express Giα2. Axons of these Giα2-ir neurons can be followed from VNO to the anterior part, but not the posterior part, of the nerve-glomerular (N-GL) layer of the accessory olfactory bulb (AOB). Another population of receptor neurons, which are located in the deep layer (basal 1/3) of the vomeronasal sensory epithelium, express Goα and axons of the Go α-ir neurons can be traced to the posterior part, but not the anterior part, of the N-GL layers of the AOB. The axons of the two subclasses of receptor neurons are intermingled near the VNO and become segregated as they enter the AOB. Removal of the AOB results in retrograde degeneration of both Giα2-ir and Goα-ir receptor neurons in the VNO. These results suggest that at least two subclasses of receptor neurons exist in the VNO: the Giα2-ir neurons in the middle layer and the GO.-it neurons in the deep layer of the VNO. The Giα2-ir neurons in the middle layer of the VNO project to the anterior part of the AOB, while the Goα-ir neurons in the deep layer of the VNO project to the posterior half of the AOB. These results are similar to our previous observations in the gray short-tailed opossum, suggesting that the existence of at least two subclasses of receptor neurons in the vomeronasal epithelium with differential projections to the AOB is a conserved feature among mammals. |
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