Stem-cell area of interest refers to a microenvironment, inside the particular anatomic location the place stem cells are found, which interacts with stem cells to regulate cell destiny. The phrase ‘area of interest’ can be in reference to the in vivo or in vitro stem-cell microenvironment. During embryonic growth, numerous niche factors act on embryonic stem cells to alter gene expression, and induce their proliferation or differentiation for the development of the fetus.