Development
During the stage of neural plate formation the embryo consists of three cell layers: the ectoderm that eventually forms the skin and neural tissues, the mesoderm that forms muscle and bone, and the endoderm that will form the cells lining the digestive and respiratory tract. The progenitor cells that make up the precursors to neural tissues in the neural plate are called neuroepithelial cells. BMP-4 is a transforming growth factor that causes the cells of the ectoderm to differentiate into skin cells.
Without BMP-4 the ectoderm cells would automatically develop into neural cells. Axial mesoderm cells under the ectoderm secrete inhibitory signals called chordin, noggin and follistatin. These inhibitory signals inhibit BMP-4 and as a result cause the overlying cells of the ectoderm to develop into neural cells. The cells in the ectoderm that circumvent these neural cells do not receive the BMP-4 inhibitor signals and as a result BMP-4 induces these cells to develop into skin cells.
As the neural plate develops, it becomes surrounded by neural folds, which eventually create the cylindrical neural tube. This process is termed primary neurulation.
Read more about this topic: Neural Plate
Famous quotes containing the word development:
“Other nations have tried to check ... the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.”
—John Louis O’Sullivan (1813–1895)
“The man, or the boy, in his development is psychologically deterred from incorporating serving characteristics by an easily observable fact: there are already people around who are clearly meant to serve and they are girls and women. To perform the activities these people are doing is to risk being, and being thought of, and thinking of oneself, as a woman. This has been made a terrifying prospect and has been made to constitute a major threat to masculine identity.”
—Jean Baker Miller (20th century)
“Dissonance between family and school, therefore, is not only inevitable in a changing society; it also helps to make children more malleable and responsive to a changing world. By the same token, one could say that absolute homogeneity between family and school would reflect a static, authoritarian society and discourage creative, adaptive development in children.”
—Sara Lawrence Lightfoot (20th century)