DAO 42:101-110 (2000)  -  doi:10.3354/dao042101

Glycogen granules in resting and inflammatory rainbow trout phagocytes‹an ultrastructural study

António Afonso1,2,*, Paula M. Macedo1, Anthony E. Ellis3, Manuel T. Silva1

1Institute for Molecular and Cell Biology, University of Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
2Abel Salazar Biomedical Institute, University of Porto, Largo Abel Salazar 2, 4099-003 Porto, Portugal
3Marine Laboratory, Fisheries Research Services, PO Box 101, Victoria Rd, Aberdeen AB11 9DB, United Kingdom

ABSTRACT: The ultrastructural image of glycogen granules in the cytoplasm of rainbow trout phagocytes in sections stained by the conventional lead or uranyl-lead stains is highly dependent on fixation conditions, the granules being visible only when adequate fixation protocols are used. Morphometry of samples processed for the detection of peroxidase or esterase activities (to specifically label neutrophils and macrophages, respectively), and simultaneously stained for the specific detection of glycogen, showed that inflammatory peritoneal neutrophils were richer in glycogen granules than resting neutrophils. This increase in glycogen content occurs after the migration from the haematopoietic tissues and peripheral blood to the inflamed foci. Glycogen granules could not be found in resting peritoneal macrophages but were found in inflammatory macrophages. The macrophage granules occurred in smaller amounts than in neutrophils, and consisted of granules identical to those of neutrophils together with significantly smaller granules. No evidence for the utilization of glycogen by neutrophils phagocytosing bacteria within the peritoneal cavity was found.


KEY WORDS: Glycogen granules · Neutrophils · Macrophages · Phagocytosis · Fish


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