Mitosis is the process of cell division that begins after conception, where the single-celled zygote divides exponentially. This fragile process involves the cell count growing from one to two, four, eight, and so on. Due to the delicate nature of this stage, fewer than half of all zygotes survive the first two weeks. As mitosis continues, the dividing cells become increasingly specialized, laying the groundwork for the formation of different organs and body parts.