Which stem cells can form almost all types of cells in the body, excluding extra-embryonic tissue?

Pluripotent stem cells possess the unique ability to differentiate into nearly all cell types found in the body, specifically those from the three germ layers: ectoderm, mesoderm, and endoderm. This capacity allows them to give rise to a myriad of tissues and organs, such as muscle, nerve, and blood cells, making them a key component in tissue engineering and regenerative medicine. However, they do not have the capability to develop into extra-embryonic tissues, like the placenta, which is a characteristic of totipotent stem cells.

Totipotent stem cells can generate both embryonic and extra-embryonic tissues, but they are limited to the earliest stages of development. Mesenchymal stem cells, while versatile and capable of forming a limited range of specialized tissues like bone, cartilage, and fat, do not have the same expansive differentiation potential as pluripotent stem cells. Hematopoietic stem cells are specifically responsible for generating blood cells and do not have the ability to differentiate into all cell types. Thus, among the options, pluripotent stem cells are the most appropriate choice for their capability to develop into almost all cell types in the body, excluding extra-embryonic tissue.