<P> Red blood cells or erythrocytes, primarily carry oxygen and collect carbon dioxide through the use of haemoglobin, and have a lifetime of about 120 days . In the process of being formed they go through a unipotent stem cell stage . They have the job alongside the white blood cells of protecting the healthy cells . </P> <P> RBCs are formed in the red bone marrow in the adults . After the completion of their lifespan, they are destroyed in the spleen . </P> <P> White blood cells or leukocytes, are cells of the immune system involved in defending the body against both infectious disease and foreign materials . Five diverse types of leukocytes exist, and are all produced and derived from multipotent cells in the bone marrow known as a hematopoietic stem cells . They live for about 3 to 4 days in the average human body . Leukocytes are found throughout the body, including the blood and lymphatic system . </P> <P> The two main categories of white blood cells are granulocytes and agranulocytes . </P>

Where are red and white blood cells produced