(3H)morphine localization in myenteric plexus.

Preferential binding of 3H-labeled morphine to satellite cells, but not to large neurons in the myenteric plexus, is demonstrated autoradiographically. Microfluorometric spectra of the plexus show nerve fibers that contain norepinephrine and impinge on satellite cells. Cells containing serotonin occur occasionally on longitudinal muscle outside the myenteric plexus.