HeLa cell division Coloured scanning electron micrograph SEM of a HeLa cell undergoing the final stage of cytokinesis cell division Cytokinesis occurs after nuclear division mitosis which produces two daughter nuclei The two daughter cells are still connected by a midbody a transient structure formed from microtubules pink centre HeLa cells are a continuously cultured cell line of human cancer cells which are immortal and so thrive in the laboratory They are widely used in biological and medical research Magnification x when printed at centimetres tall