Description:
<p>The Mexican axolotl, a neotonous salamander, has found widespread use as an experimental animal for studies in embryology and physiology. The convenience with which the axolotl can be maintained as a laboratory animal and the high quality of the eggs it produces contribute to its popularity in laboratory research. A large array of mutant genes has been recognized in the axolotl. These genes affect one or another process during development of the organism, and have provided a basis for carrying out research in developmental genetics. Approximately three dozen mutant genes in the axolotl are known. These genes have been grouped into 5 different categories which reflect, for the most part, the developmental stage at which the mutant phenotype can first be recognized. One group of mutant genes, the autonomous cell-lethals, is discussed in detail. These genes share the common feature that homozygous embryos cannot be rescued by parabiosis with normal embryos. In addition, grafts of mutant tissue (e.g., gill or limb primorida) do not survive on normal hosts. These genes probably are responsible for metabolic or regulatory defects which affect all cells and tissues in the organism. The mutant phenotypes and potential usefulness of these genes are discussed in detail.</p>