POSTEMBRYONIC DEVELOPMENT OF CORAZONIN-CONTAINING NEURONS AND NEUROSECRETORY-CELLS IN THE BLOWFLY, PHORMIA-TERRAENOVAE

An antiserum against the cockroach cardioactive peptide corazonin was used to investigate the distribution of immunoreactive neurons and neu rosecretory cells in the nervous system of the blowfly, Phormia terrae novae, during postembryonic development. A small number of corazonin-i mmunoreactive neurons was found at larval, pupal, and adult stages. At all postembryonic stages two cell groups were found in the protocereb rum of the brain: 1) two lateral cell clusters and 2) two median cells . In the larva eight bilateral cell pairs were found in thoracic and a bdominal neuromeres of the fused ventral ganglion. The lateral brain n eurons are located in the lateral neurosecretory cell group and extend axons with branches in several components of the retrocerebral neuroe ndocrine complex, in the stomatogastric nervous system of larvae and a dults, and additionally in muscles of the alimentary canal in the adul t. The most prominent element of these peripheral processes is a large plexus of varicose fibers located in the wall of the aorta, the main site for the release of neurohormones produced in the brain of blowfli es. The presence of corazonin-immunoreactive material in the aortic pl exus suggests that this peptide functions as a neurohormone. During me tamorphosis, the immunoreactive neurons found in the thoracic-abdomina l ganglion of the larva disappear, and in the brain new immunoreactive neurons are added to those that persist from larval stages. The bulk of the corazonin-immunoreactive material extracted from adult brains a nd corpora cardiaca-aorta complexes was found to co-elute with synthet ic corazonin in reversed-phase high-performance liquid chromatography as monitored with enzyme-linked immunosorbent assay. (C) 1994 Wiley-Li ss, Inc.