Cellular differentiation is a concept from developmental biology describing the process by which cells acquire a 'type'. The morphology of a cell may change dramatically during differentiation, but the genetic material remains the same, with few exceptions. A cell that is able to differentiate into many cell types is known as pluripotent. These cells are called stem cells in animals and meristematic cells in higher plants. A cell that is able to differentiate into all cell types is known as totipotent. In mammals, only the zygote and early embryonic cells are totipotent, while in plants, many differentiated cells can become totipotent with simple laboratory techniques. This new book presents leading-edge research from around the world in this field.