To examine the fate of the injected peritoneal mast cells (PMCs), we injected PMCs (500 or $10^5$) derived from WBB6F1-green fluorescent protein(GFP) mice into stomach wall of $WBB6F1-W/W^v$ mice. When 500 PMCs were injected, the proportion of alcian blue $(AB)^+$ mast cells to $GFP^+$ mast cells in the muscle was 25.0% on day 1, but decreased to 0.9% on day 7. Then, it increased to 98.2% on day 35. In contrast,$GFP^+$ mast cells in the mucosa were not detectable on day 1, 3, and 7 after injection. On day 35, the proportion of $AB^+$ mast cells to $GFP^+$ mast cells in the mucosa was 97.0%. When $10^5$ PMCs were injected, the proportion of $AB^+$ mast cells to $GFP^+$ mast cells in the muscle was more than 88.2%, and that in the mucosa was more than 86.3% from day 1 through 35 after injection. These results indicated that percentage of degranulation on day 1, 3, 7, 14 after injection of 500 PMCs was significantly higher than that after injection of $10^5$ PMCs. Futhermore, when 500 PMCs were injected, protease expression phenotypes of PMCs changed from day 14 after injection. When $10^5$ PMCs were injected, protease expression phenotype of PMCs did not change after injection. Such degranulated PMCs may acquire the new phenotype and adapt the new tissue.