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		Developmental Effects of Transplantation of Cell and Tissue between Axolotl Embryos David Lawrence, Franklin and Marshall College, Developmental Biology From the various microsurgical procedures of Spemann and others, several developmental principles have emerged about amphibian embryos. One of the most important discoveries was the understanding that the developmental fates of various groups of cells are not rigidly determined early in development. In many cases, if a multicellular fragment of an early frog gastrula is transplanted from one region of the embryo to another, the cells will behave as if they were cells from the inserted site, producing structures that would normally develop in that part of the embryo. Later in development, however, cells of transplanted fragments develop differently. They tend to continue along the same developmental pathways that they would have followed in their original location. They differentiate as if they had not been transplanted, thus producing an anomalous patch of misplaced tissue. Experiments by DuShane in the 1930s revealed that the neural crest elements are precursors of pigment cells. To demonstrate that the pigment cells are derived from the neural crest, we plan to transplant the crest material to another region of the frog's body. Neural crest cells form a dorsally placed wedge between the lateral wall of the neural fold and the ectoderm on each side of the embryo, thus the removal of the lateral neural fold removes a portion of the neural crest. A young axolotl embryo.