The neurosecretory system of the adult Calliphora erythrocephala

Summary In continuation of previous light microscopical investigations using darkfield microscopy of the living cells and sections stained with paraldehyde-fuchsin, an electron microscopical study of the medial neurosecretory cells (m.n.c.) of virgin females of Calliphora has been performed. The neurosecretory material consists of elementary granules corresponding in quantity to the amount of secretory material found by the two other methods in flies of the same age and kept on the same diet. The majority of the cells (m.n.c. I) contain granules measuring c. 2000–3000 Å, while fewer cells (m.n.c. II) show a smaller granular diameter (c. 1000–1500 Å). Due to the Tyndall effect the elementary granules are visible when using darkfield microscopy.The granules were seen to be pinched off from the Golgi complexes. These are numerous and well-developed, except in the less active m.n.c. I of the six days old sugar-flies. The reticulum and mitochondria are described. Axoplasmic channels were observed in the m.n.c. I, probably corresponding to structures found by Wigglesworth (1959 and 1960) in other insect neurons with another technique.The fine structure of the giant neurons and the vacuolated cells has been studied, the observations supporting the conclusions of M. Thomsen in a light microscopical study (1965). Lacunae in the ramifying glia are interpreted as belonging to the glial lacunar system described by Wigglesworth (1960).Dedicated to the memory of Ernst Scharrer (1905–1965), pioneer in the study of neurosecretion.We are grateful to the Carlsberg Foundation and the State General Scientific Foundation for financial support.