Timelapse microscope footage of the movement and replication of HeLa cervical cancer cells in culture. Replicating cells are seen to separate their chromosomes by mitosis before dividing (cytokinesis), producing two daughter nuclei. HeLa cells are a continuously cultured cell line of human cancer cells, taken from Henrietta Lacks in 1951. The cells are immortal and so thrive in the laboratory, and they are widely used in biological and medical research. Captured at two frames per minute, with differential interference contrast illumination.