not into a fully totipotent cell, but instead into a "complex cellular variation" of totipotency.

The human development model can be used to describe how totipotent cells arise. Human development begins when a sperm fertilizes an egg, and the resulting fertilized egg creates a single totipotent cell, a zygote. In the first hours after fertilization, this zygote divides into identical totipotent cells, which can later develop into any of the three germ layers of a human