Immunocytochemical studies on the new bone of dopaminergic neurons in the mouse main olfactory bulb

Regarding dopamine (DA) activity in periglomerular cells (PGCs) of the mouse main olfactory bulb, changes in the pattern of DA-immunoreactivity (Ir) during embryonic, neonatal and adult stages were studied using an immunohistochemical method with an antityrosine hydroxylase (TH) antibody, anti-GTP cyclohydrolase I (GCH) antibody and anti-DA antibody. In some PGCs, TH-Ir was observed during an embryonic stage; that is, at 18 days after fertilization (E18), PGCs and fibers extending from PGCs were clearly stained. Then, at approximately 17th day postnatal (P17), TH-Ir, as indicated by the staining of PGCs and their fibers, reached the peak, which was maintained hereafter. On the other hand, in some PGCs, GCH-Ir was observed from approximately E18, reached the peak at P17, then decreased rapidly. From four weeks postnatal, PGCs with GCH-Ir were hardly observed. DA-Ir was observed in some PGCs at P17. These results indicate that PGCs' DA activity reaches the maximum at about P17.