Distribution of methionine-enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves in the forestomach of cattle.

The distribution of methionine-enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves in the forestomach of calves and cows was studied, using immunohistochemical methods. Methionine-enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves were found in all regions of the bovine forestomach. Cell bodies were found mainly in myenteric ganglia, and nerve fibers were found principally in muscular layers. Nerve fibers and ganglia were concentrated in the lips of the reticular groove, but were least numerous in ruminal and omasal walls. The reduced number of immunoreactive nerves in cows, compared with the number of those in calves, was striking, especially in the lips of the reticular groove and the omasal leaves. Results may indicate that the importance of methionine-enkephalin-Arg6-Gly7-Leu8-containing nerves in the physiologic regulation of the forestomach of the calf is different from that of the cow.