ABSTRACT. Development of cerebral perivascular nerves immunoreactive for vasoactive intestinal polypeptide (VIP) was investigated in the Japanese quails, using immunohistochemistry and quantitative analysis. VIP-immunoreactive (VIP-IR) nerves supplying the anterior circulation appeared on the cerebral carotid artery (CCA) at embryonic day 10 and on the cerebroethmoidal artery (CEA) after hatching. Nerves from the CCA increased greatly in number and spread progressively during successive embryonic stages, while those from the CEA were sparse all through the post-hatching stages, mostly remained limited to this vessel wall. The distribution of VIP-IR nerves to the respective major arteries of the anterior circulation from the two vascular routes was basically similar among post-hatching day (P) 15, P20, P30 and P50. Likewise, no clear statistical difference was observed with regard to the nerve density of the corresponding arteries in the four age groups. These findings suggest that VIP-IR innervation of the quail anterior circulation usually attains its mature pattern at the third week after hatching.KEY WORDS: cerebrovascular innervation, development, quail, vasoactive intestinal polypeptide.

ABSTRACT. The colocalization of immunoreactivity to nitric oxide synthase (NOS), vasoactive intestinal polypeptide (VIP) and tyrosine hydroxylase (TH) in the superior cervical ganglion (SCG) was investigated in the quail. In this bird, a substantial amount of NOS-immunoreactive (IR) cells were consistently found in the SCG without colchicine treatment or nerve ligation. The finding worthy of pointing out was that three-fourths of these NOS-IR cells were positive for TH. VIP-IR cells appeared with markedly low frequency than NOS-IR cells. They were generally small in size and often located in the ganglion peripheral. There were no VIP-IR cells positive for TH or negative for NOS: VIP immunoreactivity always appears in NOS-IR cells negative for TH. Thus, the results of the present study clearly showed the existence of two distinct subpopulations of postganglionic NOS-IR neurons (one is catecholaminergic and negative for VIP, and the other is non-catecholaminergic and positive for VIP). This suggests that nitric oxide (NO) and possibly VIP act as postganglionic neurotransmitters or neuromodulators in the quail SCG. The predominant appearance of the former category of NOS-IR cells must be considered in relation to some specific NO-induced controlling mechanisms of SCG neurons. KEY WORDS: nitric oxide synthase, quail, superior cervical ganglion, tyrosine hydroxylase, vasoactive intestinal polypeptide.