Assessment of the interbulbar connections in the cat using the Fink-Heimer and HRP methods

The anterograde degeneration technique, using the Fink-Heimer method, and retrograde cell tracing with horseradish peroxidase (HRP) were used to analyze the afferent and efferent fiber projections of the olfactory bulb complex, consisting of the main olfactory bulb (MOB), the anterior olfactory nucleus (AN) and the accessory olfactory bulb (AO) in the cat. The results reveal that the ipsilateral and contralateral fibers running via the anterior commissure to join the internal plexiform layer of both the ipsilateral and contralateral MOBs originate from the AN, whereas the ipsilateral fiber terminals running into the outer part of the plexiform layer of the pyriform cortex originate from the MOB and AOB. In consideration of the olfactory functional relays, it is suggested that the AN, both in the dorsolateral part and external layer, most likely stimulates some afferent and efferent impulses of the olfactory impact in the mammal.