Stem Cells
Blastomeres isolated from the ICM of mammalian embryos and grown in culture are known as embryonic stem (ES) cells. These pluripotent cells, when grown in a carefully coordinated media, can give rise to all three germ layers (ectoderm, endoderm, and mesoderm) of the adult body. For example, the transcription factor LIF4 is required for mouse ES cells to be maintained in vitro. Blastomeres are dissociated from an isolated ICM in an early blastocyst, and their transcriptional code governed by Oct4, Sox2, and Nanog helps maintain an undifferentiated state.
One benefit to the regulative nature in which mammalian embryos develop is the manipulation of blastomeres of the ICM to generate knockout mice. In mouse, mutations in a gene of interest can be introduced retrovirally into cultured ES cells, and these can be reintroduced into the ICM of an intact embryo. The result is a chimeric mouse, which develops with a portion of its cells containing the ES cell genome. The aim of such a procedure is to incorporate the mutated gene into the germ line of the mouse such that its progeny will be missing one or both alleles of the gene of interest. Geneticists widely take advantage of this ICM manipulation technique in studying the function of genes in the mammalian system,.
Read more about this topic: Inner Cell Mass
Famous quotes containing the words stem and/or cells:
“All things seem mention of themselves
And the names which stem from them branch out to other referents.
Hugely, spring exists again.”
—John Ashbery (b. 1927)
“Madness is locked beneath. It goes into tissues, is swallowed by the cells. The cells go mad. Cancer is their flag. Cancer is the growth of madness denied.”
—Norman Mailer (b. 1923)