SEROTONIN IMMUNOREACTIVITY IN THE CAROTID-BODY OF ADULT HUMANS

The distribution of serotonin immunoreactivity (-IR) was studied in ad ult human carotid bodies, obtained at post-mortem, using both the pero xidase-antiperoxidase method on paraffin sections and a double-labelli ng immunofluorescence on frozen sections. Antibodies against synaptoph ysin and protein gene product (PGP) 9.5 were used for identification o f serotonin-IR cells. Serotonin-IR was demonstrable in the carotid bod ies of adult humans and it was coexpressed mostly with synaptophysin o r PGP 9.5 in type I cells. Some serotonin immunopositive type I cells were located in close proximity to capillaries. Serotonin-IR was also observed in a few endothelial cells.