Pluripotent the inner cell mass are are able to differentiate to primitive ectoderm They ultimately differentiates during gastrulation into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm These include more than 220 cell types in the adult bod The inner cell mass are are able to differentiate to primitive ectoderm.  They ultimately differentiates during gastrulation into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm.  These include more than 220 cell types in the adult body