Ultrastructural localization of serotonin in the intrapulmonary neuroepithelial bodies of neonatal rabbits by use of immunoelectron microscopy.

The ultrastructural localization of serotonin in neuroepithelial bodies (NEB) of neonatal rabbits was examined by use of the recently developed immunogold-staining method. In the granulated epithelial cells of NEB serotonin-immunoreactive material could be demonstrated only in dense-cored vesicles (DCV) of the first type. No immunoreactivity was observed in DCV of the second type. The present findings support the previously made suggestion that the corpuscular NEB cells contain two distinctive DCV types which react differently with the immunogold-staining procedure for identifying serotonin. NEB, known as intrapulmonary sources of serotonin (and peptide substances), may play a prominent role in lung physiology.