Red blood cell (the remaining oxygen is carried dissolved in the blood plasma). The red blood cells of an average adult human male store collectively about 2.5 grams of iron, representing about 65% of the total iron contained in the body. Red blood cells in mammals "anucleate" when mature, meaning that they lack a cell nucleus. In comparison, the red blood cells of other vertebrates have nuclei; the only known exceptions are salamanders of the genus "Batrachoseps" and fish of the genus "Maurolicus". The elimination of the nucleus in vertebrate red blood cells has been offered as an explanation for the subsequent accumulation
Blood cell were first observed by Gabriel Andral, a French professor of medicine, and William Addison, a British physician, simultaneously. Both men believed that both red and white cells were altered in disease. With these discoveries, hematology, a new field of medicine, was established. Even though agents for staining tissues and cells were available, almost no advances were made in knowledge about the morphology of blood cells until 1879, when Paul Ehrlich published his technique for staining blood films and his method for differential blood cell counting Blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a