Differential centrifugal afferents to the anterior and posterior accessory olfactory bulb.

The centrifugal afferents to the anterior and posterior divisions of the accessory olfactory bulb (AOB) were investigated after iontophoretic injections of dextranamines. Injections affecting the anterior and posterior or just the posterior division of the AOB gave rise to retrogradely labeled cells in the bed nuclei of the accessory olfactory tract and stria terminalis and in the anterodorsal medial and posteromedial cortical (PMCo) amygdaloid nuclei. Injections restricted to the anterior division of the AOB yielded similar results, although no cells were observed in the PMCo. These results demonstrate differential centrifugal inputs to the anterior and posterior divisions of the AOB, probably to the granular layer, and provide further support for the hypothesis of a functionally segregated vomeronasal system.