Neoplasia and its possible relationship to induction

The inductor is a substance that is found in the embryo. It fu..11ctions to evoke cellular proliferation and cellular differentiation. The inductor is more active in some areas of the embryo than in other areas. These active induction areas may be called induction fields. The inductor vvas dis covered in the embryo. Spemann, Vo gt , and Na.ngold made significant contributions to the field of experiro..ental embryology. The techniques developed by Vogt were supplemented by t hose developed by Spemann, and an inductoral process was demonstrated by Spemann. Three theories have been proposed to explain the nature of inductoral action . The Axial Gradient Theory was put forth by some investigators to eA~lain the inductoral process . Other investigators maintained that the inductoral process depended upon an electrical potential. These ~1vestigators supported the Potential Difference Theory of induction. These two theories lack the support of most eA~erimen­ ters. Eany phenomena cannot be explained by either the Axial Gradient 'l'heory or by the Potential Difference Theory. A ChelTi cal Theory of inductoral action was proposed. Most experimental evidence supports the theory that the inductoral process depends upon a chemical a ction. There is strong preswnptive evidence that the inductor is not destroyed vmen the embryonic processes cease. The inductor may be present in every cell of the adult.. The evidence from normal cell replacement and from wound healing supports the theory that the inductor is present in the adult . The experimental results from regeneration i