Embryonic Induction & its role in
The Development of the Vertebrate Eye
The migration of cells is important during many stages of development, from the early events of gastrulation to the formation of the nervous system during morphogenesis. Among other processes, cell movement involves cell o cell interactions and cell to substrate interactions. These phenomena are largely dependent on the changing patterns of cell adhesion. As the migrating cell travels it continuously extends projections that probe the nature of the environment as the cell almost literally feels its way towards its ultimate target site. In the embryonic development of mammals, all of the blastomeres receive equivalent sets of determinants. Body form is determined by cell to cell interactions, a pattern called regulative development. The importance of cell to cell interactions in development is clearly demonstrated by separating the cells of an early blastula and allowing them to develop independently. Under these conditions, blastomeres of the animal pole develop features of the endoderm, but none ever develop features characteristic of the mesoderm. If however these animal pole blastomeres are placed next to those of the vegetal pole, some of them develop into mesoderm. This shows that the interaction between the cells is greatly influential in the developmental path of the cells. This process by which a cell’s path is determined as a direct result of the interaction with an adjacent cell of different history and property is called Induction. Inductive interactions involve two components, namely an inducer; the tissue that produces the signal which changes the cellular behavior of the other, and the responder; the tissue being induced. One cell is able to induce developmental changes in a neighboring cell by secreting proteins that act as intercellular signals. These signal proteins are then able to alter the pattern of gene control, thereby producing a change in...
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