“…and biochemical studies have demonstrated that both enzymes are portions of the same molecule, and a NADPH-drevealing histochemical method is currently being utilized to confirm nitrergic neurons (BREDT et al, 1990;DAWSON et al, 1991). In birds, VIP- (SUNDLER et al, 1979;VITTORIA et al, 1992;LOPEZ et al, 1993;KUENZEL and BLAHSER, 1994) and NOS-containing neurons (LI et al, 1994;BoRos et al, 1994;BRUNING et al, 1994;HIRAMATSU and OHSHIMA, 1994;BALASKAS et al, 1995) have been detected in several organs but never in the genital tract, at least to our knowledge. This study was thus made in order to explore the presence and distribution of VIP and NOS in the oviduct of the hen by means of histochemical and Immunohistochemical techniques.…”