Localisation of pancreatic polypeptide (PP)-like immunoreactive material in neurones of the brain of the blowfly, Calliphora erythrocephala (Diptera).

The brain of the blowfly, Calliphora erythrocephala, has been studied by means of the peroxidase-antiperoxidase immunocytochemical method, with the use of antibodies to bovine pancreatic polypeptide (BPP). A number of immunoreactive neurones have been localised, some corresponding to neurones previously identified tentatively as neurosecretory. This finding is further evidence that biologically active peptides, previously considered to be "vertebrates", also exist in invertebrates. It also supports the concept of their evolutionary origin in nervous tissue.