Localization of peptides in nerve terminals in the paracervical ganglion of the rat by light and electron microscopic immunohistochemistry: enkephalin and atrial natriuretic factor.

Enkephalin- and atrial natriuretic factor-like immunoreactivities were localized in nerve terminals in the female rat paracervical ganglia. Immunoreactive terminals were adjacent to and in synaptic contact with many, but not all, principal neurons. Immunoreactivity was restricted to large dense-core synaptic vesicles. These results suggest that there is a complex synaptic input to the principal neurons of the rat paracervical ganglia and that these substances could act as neurotransmitters or neuromodulators in the ganglion.