tiny red dots under the skin that are the result of very small bleeds plasma - the watery, liquid part of the blood in which the red blood cells, the white blood cells, and platelets are suspended platelets - cells found in the blood that are needed to help the blood to clot in order to control bleeding; often used in the treatment of leukemia and other forms of cancer pluripotent stem cell - the most primitive, undeveloped blood cell purpura - the purple color of skin after blood has "leaked" under it, such as in a bruise