IN-VIVO EVIDENCE THAT THE PREMATURE DEATH (P) MUTATION OF AMBYSTOMA-MEXICANUM AFFECTS AN EARLY SEGREGATING SUBPOPULATION OF NEURAL CREST CELLS

The premature death (p) mutation of Ambystoma mexicanum causes a varie ty of abnormalities and rapid degeneration in homozygous embryos. We h ave previously determined that the differentiative ability of the chon drogenic neural crest is severely deficient in these embryos. In this study, we demonstrate that the axial specification of the defective ne ural crest cells is normal, since their major migration routes are the same as those of wild-type cells from the same axial levels. In addit ion, we use a series of transplantations and extirpations to show that other neural crest cell populations are also affected by the mutation . The defects observed in pip embryos, therefore, suggest a role for t he neural crest in the morphogenesis of the gills in the establishment of a functional circulatory system, and perhaps in the proper develop ment of other organ systems. We propose that the subset of neural cres t cells which are affected by the mutation may represent an intermedia te subpopulation produced during the segregation of the neural crest. (C) 1994 Wiley-Liss, Inc.