| The zebrafish, Danio rerio, which initially prominent in developmental biology,has emerged as a powerful new vertebrate model study both human and fish diseasenow. The zebrafish has both innate immune system and adaptive immune system,which has proven to be remarkably similar to that of humans. The bacterial and viraldisease models with the zebrafish to study immune responses to infection havedeveloped for many years, and the results of these studies will provide important cluesfor the development of effective vaccines and prophylactic measures against bacterialand viral pathogens in economically important fishes and human. The presence ofmast cell (MC) has been reported in all classes of vertebrates, including many teleostfish families. The MC of teleosts, both morphologically and functionally, shows aclose similarity to the mast cells of mammals. MC is immune-related cells, who playan important role in some allergic diseases, parasitic infections, certain non-specificinflammation and cances as a crucial component in both innate and acquired immuneresponses. Much about its function has been unravelled, but there remains more to beuncovered.In order to compare the difference in morphological characteristics of thedifferent granulocyte and different hematopoietic organs of zebrafish, smears stainedby Wright’s-Giemsa of whole blood, kidney, liver and spleen were used. The resultswere as follows: significant differences were observated in different granulocyte.While, the difference between different hematopoietic organs was not significant;Hematoxylin-eosin (HE) staining, Toluidine blue (TB) staining, Alcian blue-periodic acid sthiff (AB-PAS) staining, Masson trichrome staining and May-Grünwald Giemsa(MGG) staining were used to investigate the histochemical property of the MC in thedigestive tract and gills of zebrafish. The results showed that, AB-PAS and TBstaining were the best way to detect mast cells, followed by MGG; MC in thedigestive tract of zebrafish was also observed under electron microscopy. Most of theMC were mature, and were similar to mammal. But the zebrafish mast cells were lackof granular substructure.In order to study the development of MC in hematopoietic organs of zebrafish,the sizes, morphological characteristics and percentages of MC and the patterns ofdevelopments of MC were ultimately observed through the observation on the smearsstained by Wright’s-Giemsa. The results were as follows: The development of MC inzebrafish could be divided into three stages: the primitive stage, the immature stageand the mature stage. The primitive cells of granulocyte appeared in all three organs,but most of them were found in kidney. Therefore, kidney was the principalhematopoietic organ, and the spleen and the liver were auxiliary organs.We observed the distribution characteristics of the MC in digestive tract, gills,kidney, liver and spleen by histochemical staining method. It was demonstrated thatzebrafish mast cells contain tryptase in their cytoplasm by SABC immunohistochemi-cal techniques with a murine mono clonal antibody TPSAB1raised against humanmast cell tryptase. Small amount of the positive tryptase cells were found in tissues.Although the distribution characteristics were different, there were two common: MCin organs were often distributed in shallow; MC often appeared nearby the bloodvessels, nerves and lymphatic glands.In this study, zebrafish model indueced by Edwardsiella tarda (E. Tarda) wasused to investigate the interactions between enteritis and MC. Intraperitoneal (IP)injection of live E. Tarda resulted in visible sign of enteritis. Infected intestines hadlarger numbers of MC, which often appeared in the epithelial layer and in closeproximity to, and inside, the blood capillaries. Degranulation of MC was significantcompared with saline-injected controls. Therefore, we conclude that, MC hadparticipated in the enteritis and may play an important role in immune response. |
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