: Fates of degranulated mast cells by challenge of the homologous antigen to the Clonorchis sinensis infected rats, and the extruded granules were examined by means of light and electron microscopy. The whole experiment was carried out six weeks after the Clonorchis infection and an observation was made at 1, 3, 5, 8, 12 hours after the antigen challenges. The abdomen of the infected rat was cut open by 2 centimeters and the antigen was directly inoculated to mesentery, then again sutured. According to the scheduled period, the rat was sacrificed. The challenged portion was cut out and followed by dying procedure. The results of the observation are summarized as follows: Degranulation was observed within one hour without noticeable change of the granules. Three hours after the inoculation, the shed granules were phagocytized by macrophage surrounding the mast cells. They were aggregated in the cytoplasm. In 5 days phagocytosis phenomenon were almost completed but still some granules were scattered in surroundings upto 12 hours. The nucleus of the degranulated cell appeared clearly in contrast to normal cells which were killed with granules. Membrane became to normal, and the granules which were not expelled out agglomerated in a large cavity. The above resulst suggest that the partially degranulated mast cells do not disintegrate, but recover to normal, and expelled granules are phagocytized by macrophages.
