selective immunocytochemical procedures , applied at the light and electron microscopical level , have resulted in the identification of three types of enkephalin-immunoreactive nerves in the feline gastrointestinal tract , including neurons containing either met- or leu-enkephalin immunoreactivity or those simultaneously storing both met- and leu-enkephalin immunoreactants .
C0014298
enkephalin
C0014294
leu-enkephalin