Fig. 4. GABA and VIP immunoreactivities in the gastrointestinal tract of Xenopus laevis. (A) GABA-immunoreactive bipolar nerve cell body in the myenteric plexus of the cardiac stomach. (B) Extensive network of GABA-immunoreactive nerve fibres in the myenteric plexus of the rectum. (C,D) Double-staining of nerve fibres in the myenteric plexus of the rectum. Most GABA-immunoreactive nerve fibres are not VIP-immunoreactive and vice versa. Bars: 25 µm (A,C,D) 50 µm (B).