[Immunocytochemical demonstration of neuropeptides (neurophysin and oxytocin) by the protein A-gold technic].

In the classic peptidergic neurosecretory system of vertebrates the neurohormone oxytocin is associated with the carrier protein neurophysin. By using small gold particles (3 to 12 nm) in the protein A-gold technique, both the hormone and the carrier-protein will be labelled, while larger particles (20 nm) label only the neurophysin. To bind the latter particles, a greater number of Fc-regions of antigen-IgG-complexes seems to be necessary.