What type of stem cells can give rise to any cell type in an organism?

Totipotent stem cells are unique in their ability to give rise to any cell type in an organism, including both embryonic and extraembryonic tissues. This capability means that a single totipotent cell has the potential to develop into a complete, viable organism.

Totipotent stem cells are present during the earliest stages of embryonic development, specifically the fertilized egg (zygote) and the initial divisions that follow. At this stage, the cells retain the full developmental potential to differentiate into any cell type necessary for forming organs, tissues, and also supporting structures such as the placenta.

In contrast, pluripotent stem cells can become any cell type within the three germ layers: ectoderm, mesoderm, and endoderm, but they cannot form extraembryonic tissues like the placenta. Multipotent stem cells are more limited; they can develop into multiple cell types within a specific tissue or organ but not into every type of cell in the body. Unipotent stem cells can only differentiate into one cell type, thus having the most restricted potential.

This distinction makes totipotent stem cells critically important in early development and regenerative medicine.