Totipotency of cells means that differentiated cells still have the potential to differentiate into new individuals. High specialization inhibits the totipotency of animal cells. Animal cells replicate the chromosomes of the mother cell through mitosis and accurately distribute them to two daughter cells. Because there are genetic materials on chromosomes, the stability of traits is maintained between parents and offspring of animals. This makes differentiated or undifferentiated animal cells have the potential to develop into various tissues of complete organisms.

There is a sharp contradiction between the totipotency of higher animal cells and the specialization of cell functions. An inevitable result of cell totipotency is that the development of its various functions is limited, because any function must have its own material basis, and each function needs its own specific material basis different from other functions. That is, the development of each function must be based on the increase in the number of its specific material structure and the specialization of its structure. If a cell wants to develop its various functions highly, it is inevitable that the bigger the cell, the better, but this is strictly limited by nature. Therefore, cells either maintain "omnipotence" and the development of various functions is limited and at a low level, or specialize at the expense of "omnipotence", thus greatly improving the efficiency of a certain function. You must choose one of the two, but you can't "have the best of both worlds."

Therefore, scientists first start with the early embryos of low-differentiated higher animals, and then study embryo segmentation and nuclear transfer.