The neurosecretory system of the adult Calliphora erythrocephala

Summary The histology of the corpus cardiacum (c. card.) and the hypocerebral ganglion of Calliphora has been described from sections mainly stained with paraldehyde-fuchsin (PAF) and counterstained with Halmi's mixture. Concurrently the nervous connections of these organs with the neurosecretory system and the stomatogastric nervous system were studied.Neurosecretory material from the medial neurosecretory cells of the brain (m.n.c.) could be traced through the cardiac-recurrent nerve, and passing through the c. card. it was seen to be abundantly present in the wall of the aorta and the two pairs of nerves leaving the c. card.-hypocerebral ganglion complex posteriorly, i.e. the aortic and the oesophageal nerves. However, in some old, fed flies a considerable amount of neurosecretory material was also observed in anastomosing branches of the cardiac-recurrent nerve inside the c. card. Thus storage of neurosecretory material originating in the m.n.c. may take place both in the aorta wall and in the c. card. This observation is relevant to the interpretation of previous experiments of E. Thomsen (1952).The c. card. cells proper (the c.n.c.) were not stained by the PAF, although they are known to be neurosecretory.This work was supported by grants from the Carlsberg Foundation. I am grateful to Professor C. Overgaard Nielsen for laboratory facilities.