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Histochemical observations on the occurrence of carbohydrates, lipids and enzymes in the daughter sporocyst of Cercaria bucephalopsis haimaena Lacaze-Duthiers, 1854 (Digenea: Bucephalidae).
Published online by Cambridge University Press: 06 April 2009
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The distribution of carbohydrates, lipids and enzymes in the daughter sporocyst and contained cercariae of Cercaria bucephalopsis haimaena Lacaze-Duthiers, 1854, is mapped and used as an indication of metabolism. It is concluded that host glucose, glycogen, fatty acids and neutral lipids are absorbed and pass through the syncytial tegument into the cellular sub-tegument. They are then either metabolized or passed into the body cavity and contained cercariae. Glucose seems to be either converted into glycogen and glycoproteins or metabolized anaerobically. The end products of anaerobic respiration are fatty acids and neutral lipids. These pass into the excretory system, which flushes them into the body cavity of the daughter sporocyst, from where they enter the body of the developing cercariae. In the cercariae they are deposited, together with host lipids, possibly as less toxic higher fatty acids or other stored lipids. The stored glycogen and lipids in the cercariae are probably utilized aerobically during the free-living existence. The transport of nutrients and excretory products across the cell membranes may be aided by alkaline phosphatase and esterase activity, as is the metabolism of carbohydrates and lipids. Acid mucopolysaccharide precursors appear to be synthesized in the dense cytoplasm of the mid-tegument of the daughter sporocyst and secreted into the host's visceral haemocoel. Acid phosphatase and esterase found in this region may be involved in the synthesis and also in the breakdown of complex incoming nutrients.
We are grateful to Professor E. W. Knight-Jones for laboratory facilities and to the Science Research Council for a grant to one of us (E. A. B.) which made the work possible.
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- Copyright © Cambridge University Press 1967
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