XB-IMG-170643
Xenbase Image ID: 170643
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Figure 8. (A) Control of protrusive rates and orientation by FN/integrin interactions. Superactivation of integrins with Mn2+ results in reduced protrusive rates whereas removal of FN fibrils or inhibition of α5β1 enhances the frequency of protrusions and results in loss of mediolateral orientation.
(B) Effective convergence and extension requires maintenance of a two-cell layered mesoderm. Closer inspection of mediolateral cell intercalation (within circle) reveals an underlying cellular mechanism.
(C) Tractive protrusions (red arrows), balanced along mediolateral contacts with neighboring cells, directs cell intercalation and separates neighboring cells along the anterior-posterior axis (a, anterior; p, posterior). Balanced, directed intercalation maintains the two-cell layers of the mesoderm and leads to the efficient conversion of convergence into axial extension.
(D) Without a balance of forces, tractive protrusions may be directed either over the top of neighboring cells or underneath neighboring cells (single red arrows). In this case, cells converge to the midline but become multilayered. Without maintenance of two-cell layers, cell intercalation results in tissue thickening.
All views are “cut-away” transverse perspectives, centered on the notochord where the mediolateral axes run left and right and the anterior posterior axis runs toward and away (no, notochord; so, somitic mesoderm; ne, neural ectoderm; en, endoderm; d, dorsal; v, ventral). Image published in: Davidson LA et al. (2006) Copyright © 2006. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View |