Stem cells are unspecialized cells that are capable of differentiating into other cells and self-regenerating. The ability to differentiate means the potential to develop into other types of cells.
A totipotent stem cell, also known as fertilized egg, can develop into all cell types, such as the embryonic membranes. A pleuripotent stem cell has the ability to develop into cells from all three germinal layers, which refer to cells from the inner cell mass. Self regeneration means stem cells can divide and produce additional stem cells. The cell division is symmetrical during early development, meaning every cell divides to produce daughter cells with the same potential. The cell later divides asymmetrically, with one daughter cell being a stem cell, and the other becoming a more differentiated cell.
It is explained that stem cells can divide for long periods, unlike most cells, such as skin cells, that cannot replicate themselves after a specific period. Stem cells self-sustain by replicating themselves. Moreover, unlike specialized cells which have particular capabilities that enable them to perform certain tasks, they do not have tissue specific structures to carry out specialized functions. However, they can produce specialized cells through the process differentiation and form special cell types.