Heterogeneity of motilin-immunoreactive cells in the duodenum and pyloric region of several avian species.

Immunohistochemical characterizations of motilin-immunoreactive cells were examined in gastric and duodenal mucosae of nine species of birds from seven orders using five different region-specific motilin antisera. Motilin-immunoreactive cells appeared as open-type cells in the mucosal epithelium and showed varying immunoreactivities to antisera used in all the birds examined except for the cormorant and penguin, which did not show any kinds of immunoreactivity to motilin. Motilin-immunoreactive cells of the emu duodenum were detected by all the motilin-antisera used. The present results suggest that there is a wide range of heterogeneity between motilin molecules among avian species, or perhaps alternatively the existence of a family of motilin-like peptide. Furthermore, the present results should prove useful for a molecular biological study on the evolution of avian motilin.