Three-dimensional distribution of vasoactive intestinal polypeptide-containing structures in the rat stomach and their origins using whole mount tissue.

The three-dimensional distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactive (VIPLI) structures in rat stomach and their origins were investigated using the indirect immunofluorescence method in whole mounted tissue. The present study demonstrates a very dense VIPLI fiber meshwork in the circular muscle layer, longitudinal muscle layer and myenteric plexus. In the muscle layers VIPLI immunoreactive fibers run parallel to the muscle. VIPLI fibers are distributed evenly throughout the entire stomach. We have also shown by experimental manipulations that the fibers in the stomach originate from VIPLI neurons in the myenteric plexus.