Fig. 1.

Schematic representation of stem cell hierarchy. Stem cells are distinguished by their potential to differentiate into a specialized cell type. The totipotent stem cell, which emerges from the fertilization of an egg, remains at the top of the stem cell hierarchy. The totipotent stem cell produces a blastocyst after a series of divisions, containing ESCs at the inner cell mass. ESCs are pluripotent and can thus give rise to all cell types in our body, including somatic stem cells or adult stem cells, which, on the other hand, are multipotent and have a more limited ability to differentiate, being committed to a specific lineage