Studies on the Phagocytic System in Goldfish-I

The phagocytic system in goldfish was studied through intraperitoneal injection with India ink. Fish were killed at intervals ranging from 30 min to 50 days after injection. Histological research was performed on spleen, kidney, heart, liver, gills and blood.On the first day after injection, the spleen and kidney became black. Phagocytosis of carbon particles was performed from the first day after injection by the sheath cells in the sheathed artery of the spleen, by the reticuloendothelial cells throughout the haematopoietic tissue of the kidney, and by the endothelial cells in the ventricle of the heart. Carbon phagocytizing macrophages in the kidney and spleen formed aggregates within pre-existing aggregates of melano-macrophage on the fourth day after injection. Those aggregates were observed for 50 days. There was no phagocytosis of carbon particles observed in the liver and gills.Two types of mononuclear phagocytes phagocytizing carbon particles were observed in smears of blood. The large phagocytes measured between 14 and 16μ in diameter and the nucleus occupied almost half of the cell. The small phagocytes measured between 6 and 7μ in diameter and the nucleus occupied almost all of the cell. Although the small phagocytes were observed in smears during the period from the first day to the thirty-sixth day after injection, the large ones were only observed from the first day to the seventh day.The significance of the phagocytic system in fish is discussed.