Talk about Mastocytes.

Cells of tissues, basophilic granules and mast cells are two types of cells derive from same determined (specialized) cell precursor in red bone marrow, found in almost all loose CT, vicinity of blood vessles and nerves (more abundant in skin respiratory tract and digestive tract) Mobile, rounded with irregular contours, small rounded central nucleus, easily recognizable by basophilic granules in cytoplasm, functions are similar to basophils.