During natural embryo development, cells undergo proliferation and specialization from the fertilized egg, to the blastocyst, to the gastrula during natural embryo development (left side of panel). Pluripotent, embryonic stem cells are derived from the inner cell mass of the blastoctyst (lightly shaded). Multipotent stem cells (diamond pattern, diagonal lines, and darker shade) are found in the developing gastrula or derived from pluripotent stem cells and are restricted to give rise to only cells of their respective germ layer.