Shih, John and Keller, Ray (1992) The epithelium of the dorsal marginal zone of Xenopus has organizer properties. Development, 116 (4). pp. 887-900. ISSN 0950-1991 http://resolver.caltech.edu/CaltechAUTHORS:20120322-130304061
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We have investigated the properties of the epithelial layer of the dorsal marginal zone (DMZ) of the Xenopus laevis early gastrula and found that it has inductive properties similar to those of the entire Spemann organizer. When grafts of the epithelial layer of the DMZ of early gastrulae labelled with fluorescein dextran were transplanted to the ventral sides of unlabelled host embryos, they induced secondary axes composed of notochord, somites and posterior neural tube. The organizer epithelium rescued embryos ventralized by UV irradiation, inducing notochord, somites and posterior neural tube in these embryos, while over 90% of ventralized controls showed no such structures. Combinations of organizer epithelium and ventral marginal zone (VMZ) in explants of the early gastrula resulted in convergence, extension and differentiation of dorsal mesodermal tissues, whereas similar recombinants of nonorganizer epithelium and the VMZ did none of these things. In all cases, the axial structures forming in response to epithelial grafts were composed of labelled graft and unlabelled host cells, indicating an induction by the organizer epithelium of dorsal, axial morphogenesis and tissue differentiation among mesodermal cells that otherwise showed non-axial development. Serial sectioning and scanning electron microscopy of control grafts shows that the epithelial organizer effect occurs in the absence of contaminating deep cells adhering to the epithelial grafts. However, labelled organizer epithelium grafted to the superficial cell layer contributed cells to deep mesodermal tissues, and organizer epithelium developed into mesodermal tissues when deliberately grafted into the deep region. This shows that these prospective endodermal epithelial cells are able to contribute to mesodermal, mesenchymal tissues when they move or are moved into the deep environment. These results suggest that in normal development, the endodermal epithelium may influence some aspects of the cell motility underlying the mediolateral intercalation (see Shih, J. and Keller, R. (1992) Development 116, 901–914), as well as the tissue differentiation of mesodermal cells. These results have implications for the analysis of mesoderm induction and for analysis of variations in the differentiation and morphogenetic function of the marginal zone in different species of amphibians.
|Additional Information:||© 1992 The Company of Biologists Limited. Accepted 28 August 1992. This work was supported by NSF grant DCB89052 and NIH grant HD25594. We thank J. P. Trinkaus for his inspiration and encouragement. We also thank Paul Wilson for his pointed criticism and support. We thank Dr Chris Kintner for his gift of antibodies. Finally, we thank Jessica Bolker, Mary Constance Lane, Susan Purcell, and Amy Sater for their insightful comments and suggestions.|
|Subject Keywords:||epithelial mesenchymal interactions, gastrulation, Xenopus, induction, organizer|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||17 Apr 2012 22:22|
|Last Modified:||26 Dec 2012 14:58|
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