DISTRIBUTION OF SUBSTANCE P-LIKE IMMUNOREACTIVE NERVOUS STRUCTURES INTHE DUCK GUT DURING DEVELOPMENT

The ontogeny and distribution of nerve cell bodies and fibers which ar e substance P-like (SPL) immunoreactive have been studied in the duck gastrointestinal tract by means of immunohistochemistry. The appearanc e of SPL immunoreactivity was observed in cell bodies of the oesophagu s, proventriculus, gizzard and antrum region at 6 days of incubation. At 9 days of incubation SPL immunoreactive nervous structures were obs erved in the whole length of the intestine. In each area of the gut, S PL immunoreactivity was initially observed in cell bodies of the myent eric plexus and then of the submucous plexus. Successively, immunoreac tive fibers appeared in the same plexuses and also in the circular mus cle, longitudinal muscle and muscularis mucosae plexus. Only around ha tching were SPL immunoreactive nervous structures seen in the mucous p lexus. It was observed that in adult ducks, immunoreactive nerve cell perikarya were less numerous than in embryos and in newly-hatched duck s. The pattern of distribution of SPL immunoreactivity in adult ducks was rather similar to that of the chick and other vertebrate species.