FIG. 4.

The multiple steps to reprogram a mature cell to a zygote cannot happen unintentionally. (A) A somatic cell must first be reprogrammed to an immature oocyte. (B) The oocyte must be provided with the necessary cell–cell interactions to fully mature. (C) Meiosis and genomic reprogramming must be intentionally suppressed during the maturation process. (D) Once mature, the oocyte nucleus must be reprogrammed to a zygotic state. (E) The newly formed zygote stimulated to divide. Cells are not drawn to scale; oocytes have roughly 1000× greater volume than skin cells (illustration is ∼200×greater).