title: Pattern regulation in the anterior half of the embryonically produced symmetrical forelimb of the axolotl, Ambystoma mexicanum.
abstract: Symmetrical forelimbs were created in the axoltl by performing surgery on embryos at stages 32-34. The technique of J.M.W. Slack (J. Embryol. Exp. Morphol., 39:151-168, 1977) was utilized. Several experiments were then performed to test the ability of these symmetrical forelimbs to participate in pattern formation. When symmetrical limbs were amputated without previous surgery, 58% failed to regenerate. When symmetrical limbs were wounded in the plane of symmetry and permitted to heal for 30 days prior to amputation, 75% failed to regenerate. When the anterior half of the symmetrical limb was exchanged with the posterior half of the contralateral forelimb followed by amputation 30 days later, both limbs failed to regenerate. When the anterior half of the symmetrical limb was exchanged with the anterior half of an asymmetrical limb followed by amputation 30 days later, the previously symmetrical limbs regenerated asymmetrical hands, and previously asymmetrical limbs failed to regenerate. These results indicate that wounding increases the occurrence of regenerative failure in embryonically produced symmetrical forelimbs. The anterior half of the embryonically produced symmetrical forelimb behaves unpredictably and in a manner not easily described with any of the current models of pattern regulation. The posterior half of the embryonically produced symmetrical forelimb behaves predictably during pattern formation.
mesh_terms: D000558:Ambystoma mexicanum; D000818:Animals; D002450:Cell Communication; D005260:Female; D005552:Forelimb / Q000196:embryology* / Q000502:physiology / Q000637:transplantation; D008297:Male; D012038:Regeneration