Ultrastructural identification of VIP-containing nerve fibres in the myenteric plexus of the rat ileum

Abstract
Summary Vasoactive intestinal polypeptide (VIP)-containing nerve fibres of myenteric plexus of the rat ileum were investigated using the pre-embedding peroxidase-antiperoxidase technique for electron microscopy. The VIP-positive fibres were characterized by a predominance of spherical agranular vesicles with a diameter of 40–55 nm. The immunoprecipitate was largely localized on the vesicle membrane. Large granular vesicles (100–144 mm) containing labelled dense cores were also present within labelled nerve profiles. Quantitative data indicate that the vesicles appeared in the following proportions: 93% small agranular vesicles and 7% large granular vesicles.