Do bones make red blood cells?
Red blood cells are made in the bone marrow. They start out with a nucleus, like other cells, but when they fill up with hemoglobin the nucleus is squished smaller and smaller until it disappears. With no nucleus, red blood cells are fragile and live only about 120 days. In your body, about 2 million red blood cells die per second! But your bone marrow produces new ones just as fast.
