平尾 温司

In order to clarify olfactory system of birds, the efferent and afferent connections of chicken olfactory bulb were investigated using with biocytin and horseradish peroxidase (HRP) methods. From the results of biocytin method, the efferent pathways of chicken olfactory bulb were classified into route 1-3.Route 1 projected to the ipsilateral hyperstriatum accessorium (HA), and hippocampus (Hp). Route 2 had the projections to ipsilateral hyperstriatum intercalatum supremum, hyperstriatum ventrale (HV), neostriatum (N), and nucleus basalis (Bas). Route 3 projected to the bilateral lobus parolfactorius, tuberculum olfactorium tractus fronto-archistriaticus, paleostriatum augmentatum, archistriatum anterior, cortex piriformis, area temporo-parieto-occipitalis, nucleus taeniae, contralateral HA, Hp, HV, N, and Bas. From the results of HRP method, the chicken olfactory bulb received the projections from nucleus septalis medialis, nucleus septalis lateralis, and Hp. In addition, it was appeared that the chicken olfactory bulb has the reciprocal connection with Hp.

The efferent and afferent connections of the bulbus olfactorium (BO) in chickens (Gallus gallus domesticus) were studied using the biocytin and horseradish peroxidase (HRP) methods. Twelve and seven fowls were used for biocytin and HRP studies, respectively. After biocytin was injected into the unilateral BO, many labeled fibers and terminal grains were seen in the bilateral tuberclum olfactorium. Labeled fibers and terminal grains were also found in the lobes parolfactorius, nucleus basalis, neostriatum (N), hyperstriatum accessorium (HA), paleostriatum augumentum (PA), archistriatum pars ventralis (AV), nucleus taeniae, cortex piriformis (CPi) and nucleus septomesencephalici (nSMT), bilaterally. After HRP was injected into the unilateral BO, retrogradely labeled neurons were found bilaterally in the HA as well as the nucleus septalis lateralis and medialis. These results show that the projections of a chicken BO in regard to CPi, Av, and TO are similar to projections of a mammalian's olfactory bulb. A projection from BO to nSMT is similar to that of a reptlian. In addition, projections of BO in regard to the PA, and projections f S to BO in the chicken have not been reported for other vertebrates.