INTRINSIC INNERVATION OF THE STOMACH OF THE FETAL PIG - AN IMMUNOHISTOCHEMICAL STUDY OF VIP-IMMUNOREACTIVE NERVE-FIBERS AND CELL-BODIES

Using an immunohistochemical technique, the presence and distribution of vasoactive intestinal polypeptide (VIP) was investigated in cryosta t sections, both tangential and transverse, of the fetal pig's stomach . In all fetuses and in all gastric segments investigated, VIP-like im munoreactive (IR) nerve-cell bodies were seen in all intramural gangli a, and VIP-IR nerve fibres were found in all layers of the gastric wal l except the tunica serosa. Consequently, VIP-IR nerve fibres were fou nd to form a periglandular network, to accompany arterioles, to interc onnect the intramural ganglia, to encircle both VIP-IR-negative and -p ositive neurons, and were found in all muscle layers. Despite the fact that VIP-IR seems to be restricted to the intramural nervous elements , some nonspecific-reacting VIP-IR glandular cells were noticed in the basal parts of the fundic, antral and pyloric gastric glands. The dis tribution pattern of VIP in the fetal pig resembles that of the adult pig. This suggests a possible functional role for VIP during fetal lif e and/or puts forward the suggestion that the stomach of a fetal pig f rom the second half of the gestation period is prepared, from then on, for postnatal function. High similarities with regard to the general distribution pattern of VIP in the stomach have also been noted betwee n the fetal pig and humans, proving once more that the fetal pig can s erve as a good animal model in several research areas. Finally, the mo rphological data provided here may, combined with the physiological si gnificance of VIP, contribute to a better insight into the physiopatho logy of economically important gastro-intestinal disorders in the pig, such as gastric ulceration.