a0b7112eab The formerly well-structured limb region at the cut edge of the stump thus forms a proliferating mass of indistinguishable, dedifferentiated cells just beneath the apical ectodermal cap. Mesenchymal cells typically leave the epithelial tissue as a consequence of changes in cell adhesive and contractile properties. The phenomena of epimorphic regeneration can be seen formally as events that reestablish continuity among tissues that the amputation has severed. Further reading[edit]. In 1883, August Weismann proposed the first testable model of cell specification, the germ plasm theory.
Flatworms are easy to obtain, and cutting the animal in half does nothing more than what the animal does to itself. A well-studied example of morphogenesis that involves ECM is mammary gland ductal branching.[6][7]. The ability to regenerate damaged human organs would constitute a medical revolution. Once the head is made, it makes the head inhibitor, and the equilibrium is restored.BoxMedical Advances in Regeneration. When a hindlimb is severed, the sciatic nerve transports transferrin along the axon and releases large quantities of this protein into the blastema (Munaim and Mescher 1986; Mescher 1992). Morphogens typically act through binding to specific protein receptors. However, the the individual cells within the field are not committed, and the cells of the field can regulate their fates to make up for missing cells in the field (Huxley and De Beer 1934; Opitz 1985; De Robertis et al. It appears that myotube nuclei are forced to enter the cell cycle by a serum factor created by thrombin, the same protease that is involved in forming clots. This mode of commitment is sometimes called conditional specification, because the fate of a cell depends upon the conditions in which the cell finds itself. This potential can also be shown by splitting the limb disc vertically into two or more segments and placing thin barriers between the segments to prevent their reunion.
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