What begins to guide the differentiation of the cells once an embryo has undergone gastrulation? Define the term "induction;" how is induction primarily mediated?
Through the formation of the gastrula, the interaction between a cell's cytoplasmic materials and its genes guides the differentiation of the cells. Once the embryo has undergone gastrulation, influences external to the cell's cytoplasm begin directing the cell's developmental direction. In the gastrula form, the extra cellular environment becomes less uniform, and, thus, the different locations of cells within the embryo expose them to different combinations of environmental factors. Termed induction, the differentiation caused by influences external to the cell is typically chemically mediated, although direct physical contact between cells can also control cell development by inhibiting cell motility and miotic activity. Induction occurs when chemicals secreted by one cell or group of cells affect the development of another cell or group of cells or when hormones from the mother affect certain developing tissues in the embryo.
