Editing Embryonic stem cell (section)

===Derivation from other animals===
<!-- Deleted image removed: [[File:ES cell derivation.jpeg|thumb|ES cells are derived from the [[inner cell mass]] of the early embryo.  This schematic shows one method of derivation. {{deletable image-caption}}]] -->
Embryonic stem cells are derived from the [[inner cell mass]] of the early [[embryo]], which are harvested from the donor mother animal.  [[Martin Evans]] and [[Matthew Kaufman]] reported a technique that delays embryo implantation, allowing the inner cell mass to increase.  This process includes removing the donor mother's [[ovaries]] and dosing her with [[progesterone]], changing the hormone environment, which causes the embryos to remain free in the uterus.  After 4–6 days of this intrauterine culture, the embryos are harvested and grown in ''in vitro'' culture until the inner cell mass forms “egg cylinder-like structures,” which are dissociated into single cells, and plated on [[fibroblasts]] treated with [[Mitomycin|mitomycin-c]] (to prevent fibroblast [[mitosis]]).  Clonal [[cell lines]] are created by growing up a single cell.  Evans and Kaufman showed that the cells grown out from these cultures could form [[teratoma]]s and [[Embryoid body|embryoid bodies]], and differentiate ''in vitro,'' all of which indicating that the cells are [[pluripotent]].<ref name="Evans M, Kaufman M 1981 154–6"/>

[[Gail R. Martin|Gail Martin]] derived and cultured her ES cells differently.  She removed the embryos from the donor mother at approximately 76 hours after copulation and cultured them overnight in a medium containing serum.  The following day, she removed the [[inner cell mass]] from the late [[blastocyst]] using [[microsurgery]].  The extracted [[inner cell mass]] was cultured on [[fibroblasts]] treated with [[Mitomycin|mitomycin-c]] in a medium containing serum and conditioned by ES cells.  After approximately one week, colonies of cells grew out.  These cells grew in culture and demonstrated [[pluripotent]] characteristics, as demonstrated by the ability to form [[teratoma]]s, differentiate ''in vitro,'' and form [[Embryoid body|embryoid bodies]].  Martin referred to these cells as ES cells.<ref name="Martin G 1981 7634–8"/>

It is now known that the [[Fibroblast|feeder cells]] provide [[leukemia inhibitory factor]] (LIF) and serum provides [[bone morphogenetic proteins]] (BMPs) that are necessary to prevent ES cells from differentiating.<ref>{{cite journal | vauthors = Smith AG, Heath JK, Donaldson DD, Wong GG, Moreau J, Stahl M, Rogers D| title = Inhibition of pluripotential embryonic stem cell differentiation by purified polypeptides| journal = Nature | volume = 336 | issue = 6200 | pages = 688–690 | year = 1988 | pmid = 3143917 | doi = 10.1038/336688a0| bibcode = 1988Natur.336..688S| s2cid = 4325137}}</ref><ref>{{cite journal | vauthors = Williams RL, Hilton DJ, Pease S, Willson TA, Stewart CL, Gearing DP, Wagner EF, Metcalf D, Nicola NA, Gough NM | title = Myeloid leukaemia inhibitory factor maintains the developmental potential of embryonic stem cells | journal = Nature | volume = 336 | issue = 6200 | pages = 684–687 | year = 1988 | pmid = 3143916| doi = 10.1038/336684a0| bibcode = 1988Natur.336..684W | s2cid = 4346252 }}</ref> These factors are extremely important for the efficiency of deriving ES cells.  Furthermore, it has been demonstrated that different mouse strains have different efficiencies for isolating ES cells.<ref>{{cite journal | vauthors = Ledermann B, Bürki K | title = Establishment of a germ-line competent C57BL/6 embryonic stem cell line | journal = Exp Cell Res | volume = 197 | issue = 2 | pages = 254–258 | year = 1991 | pmid = 1959560 | doi = 10.1016/0014-4827(91)90430-3}}</ref> Current uses for mouse ES cells include the generation of [[transgenic]] mice, including [[knockout mice]].  For human treatment, there is a need for patient specific pluripotent cells.  Generation of human ES cells is more difficult and faces ethical issues.  So, in addition to human ES cell research, many groups are focused on the generation of [[induced pluripotent stem cells]] (iPS cells).<ref>{{cite journal | vauthors = Takahashi K, Tanabe K, Ohnuki M, Narita M, Ichisaka T, Tomoda K, Yamanaka S | title = Induction of pluripotent stem cells from adult human fibroblasts by defined factors | journal = Cell| volume = 131 | issue = 5 | pages = 861–872 | year = 2007 | pmid = 18035408| doi = 10.1016/j.cell.2007.11.019| hdl = 2433/49782 | s2cid = 8531539 | hdl-access = free }}</ref>