Development of vasoactive intestinal polypeptide-immunoreactive nerves in the major cerebral arteries of the quail anterior circulation.

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.