Illustration of red blood cells and active platelets (white) in a blood vessel. Platelets, or thrombocytes, are small, non-nucleated cells formed in the bone marrow. In an inactive state they are round or oval discs. Activated platelets have dendritic processes, or pseudopodia, and are star-shaped. When activated they clump together to form blood clots. Red blood cells, or erythrocytes, transport oxygen from the lungs to the rest of the body and also remove carbon dioxide from the body by transporting it to the lungs where it is exhaled.