adult stem cell amphibian asymmetric cell division blastocyst bone marrow cancer cancer stem cell cell culture cell division cell fate determination cell signaling cell type chromosome cytokinesis cytopathology dna developmental biology embryo embryonic stem cell evolution gene gene expression gene regulatory network genome germ cell germ layer growth factor hematopoietic stem cell induction inner cell mass meristem mesenchymal stem cell metabolism morphogenesis multicellular organism multipotency muscle oligopotency platelet pluripotency progenitor cell purine rna red blood cell regulation of gene expression reversine somatic cell species sperm stem cell stem cell controversy stem cell line stem cell treatments subset systems biology totipotency unipotency volvox white blood cell worm zygote