Immunocytochemical mapping of gastrin/CCK-like peptides in the neuroendocrine system of the blowfly Calliphora vomitoria (Diptera)

Summary The distribution of gastrin/CCK-like immunoreactive material has been studied in the retrocerebral complex of Calliphora. The material reacts with antisera specific for the common COOH terminus of gastrin and CCK but not with N-terminal antisera. The three thoracic ganglia and the fused abdominal ganglia each contain a specific number of symmetrically arranged immunoreactive cells both dorsally and ventrally in pairs on either side of the midline in a sagittal plane. The neuropil of these ganglia also contains a considerable amount of immunoreactive fibres and droplets. Reconstructed axonal pathways suggest that some of the nerve fibres have their origins within the brain and/or the suboesophageal ganglion. Immunoreactive material may also be seen apparently leaving the thoracic ganglion posteriorly via the abdominal nerves, and there is strong evidence of a neurohaemal organ within the dorsal sheath in the region of the metathoracic and abdominal ganglia. There appears to be a direct correlation between the content of peptidergic material of cells and fibres and the age and diet of the flies. The corpus cardiacum contains COOH-terminal specific gastrin/CCK-like material within the intrinsic cells and in the neuropil. It is present also in the cardiac-recurrent nerve entering the corpus cardiacum anteriorly and in the nerves leaving the gland dorsoposteriorly, the aortic or cardiac nerves. It is not observed, however, in the nerves leaving the corpus cardiacum ventroposteriorly, the so-called oesophageal, gastric or crop-duct nerves. The corpus allatum and the hypocerebral ganglion do not contain immunoreactive material of this type. Gastrin/CCK-like and secretin-like immunoreactive materials appear to co-exist in the cells of the corpus cardiacum and co-existence of gastrin/CCK-like and pancreatic polypeptide like substances occurs within certain cells of the thoracic ganglion.     

The secretion of the subcommissural organ

Summary The secretion of the subcommissural organ (SCO) has been studied immunocytochemically by use of the following antisera: (1) antiserum against an aqueous extract of bovine Reissner's fiber (RF), (anti-RF-DC antiserum); (2) antiserum against the protein fraction F₁ obtained by gel electrophoresis of the aqueous RF-extract (RF-DF₁-antiserum); (3) antiserum against the protein fraction F₂ prepared in the same manner (RF-DF₂-antiserum). As shown by immunological and/or immunocytochemical experiments in bovines and rats, the three antisera are of high specificity, i.e., react exclusively with the secretion of the SCO, which appears to be a unique product of the vertebrate organism. Concerning the distribution of the reaction products within the SCO-cells, no differences were found light microscopically after use of the RF-DC-antiserum, the RF-DF₁-antiserum, or the RF-DF₂-antiserum.Comparative studies were carried out with the RF-DC-antiserum only. A positive immunocytochemical reaction of the SCO-secretion was obtained in many vertebrate species (mammals, birds, reptiles, amphibians, bony fishes, sharks, and cyclostomes). RF gives a positive reaction in mammals only; to date RF of non-mammalian vertebrates did not react immunocytochemically with the present antiserum. Comparative immunocytological studies have shown that (1) the SCO-cells of the ependymal layer as well as the SCO-cells of the hypendymal layer contain immunoreactive material, (2) in the majority of vertebrates hypendymal structures are more common than has been previously supposed, and (3) RF or constituents of this structure are produced by the SCO. The immunocytochemical studies have led to the impression that the SCO-secretion is not only discharged into the cerebrospinal fluid, but also in hypendymal vessels and/or leptomeningeal spaces, as has been postulated previously by Oksche and others (for review, see Oksche 1969).Supported by grants from the Ministry for Science and Technology of the German Democratic RepublicThe expert technical assistance of Mrs. M. Eigenbrod, Mrs. D. Naumann and Mrs. B. Wolff is gratefully acknowledgedDedicated to Professor Berta Scharrer on the occasion of her 75th birthday