2 Cellular Basis of Amphibian Gastrulation Kay Keller Department of Molecular and Cell Biology University of California, Berkeley Berkeley, California 94720 Rudolf Winklbauer Max-Planck-Institute for Developmental Biology Tubingen, Germany I. Introduction 11. Function of Bottle Cells in Gastrulation A. Bottle Cells and Invagination B. Bottle Cell Ingression and Mesoderm Formation C. Patterning of Bottle Cell Formation D. Experimental Tests of Function during Gastrulation E. Evolutionary Implications A. Description of the Process B. Extracellular Matrix of the Blastocoel Roof and the Substrate of Mesodermal Cell C. Motile Activity and Behavior of Migratory Mesoderm Cells D. Role of Cell Interactions in Mesoderm Cell Migration E. Function of Mesoderm Cell Migration in Gastrulation A. Convergence and Extension in Xenopus: Demonstration of Two Regions of B. Convergence and Extention in Other Amphibians C. Roles of the Epithelial Cells and the Deep Mesodermal Cells in Convergence and D. Convergence and Extension by Radial and Mediolateral Intercalation E. Cell Behavior during Mediolateral Intercalation F. Function of Convergence and Extension in Gastrulation A. Epiboly in Xenopus B. Epiboly in Urodeles C. Evidence for Autonomy of Epiboly 111. Mesodermal Cell Migration Migration IV. Convergence and Extension Movements Convergence and Extension in Sandwich Explants Extension V. The Ignored Movement: Epiboly V1. Involution VII. Some Other Issues to Be Explored A. Evolution and the Design of Gastrulation: Variation among Amphibians B, Significance of Cytomechanics and Cell Interactions in Populations References Currenr Topics in Developmenral Biology. Val. 27 Copynght Q 1992 by Academic Press, Inc All rights of reproduction in any form reserved 39