Mouse primitive streak forms in situ by initiation of epithelial to mesenchymal transition without migration of a cell population
Article first published online: 14 DEC 2011
Copyright © 2011 Wiley Periodicals, Inc.
Volume 241, Issue 2, pages 270–283, February 2012
How to Cite
Williams, M., Burdsal, C., Periasamy, A., Lewandoski, M. and Sutherland, A. (2012), Mouse primitive streak forms in situ by initiation of epithelial to mesenchymal transition without migration of a cell population. Dev. Dyn., 241: 270–283. doi: 10.1002/dvdy.23711
- Issue published online: 24 JAN 2012
- Article first published online: 14 DEC 2011
- Accepted manuscript online: 6 DEC 2011 02:26PM EST
- Manuscript Accepted: 20 NOV 2011
- NIH. Grant Numbers: RO1 HD034807, T32 GM008136
- NSF. Grant Number: IOS-1051294
- primitive streak;
- epithelial to mesenchymal transition;
- mouse embryo;
Background: During gastrulation, an embryo acquires the three primordial germ layers that will give rise to all of the tissues in the body. In amniote embryos, this process occurs via an epithelial to mesenchymal transition (EMT) of epiblast cells at the primitive streak. Although the primitive streak is vital to development, many aspects of how it forms and functions remain poorly understood. Results: Using live, 4 dimensional imaging and immunohistochemistry, we have shown that the posterior epiblast of the pre-streak murine embryo does not display convergence and extension behavior or large scale migration or rearrangement of a cell population. Instead, the primitive streak develops in situ and elongates by progressive initiation EMT in the posterior epiblast. Loss of basal lamina (BL) is the first step of this EMT, and is strictly correlated with ingression of nascent mesoderm. Once the BL is lost in a given region, cells leave the epiblast by apical constriction in order to enter the primitive streak. Conclusions: This is the first description of dynamic cell behavior during primitive streak formation in the mouse embryo, and reveals mechanisms that are quite distinct from those observed in other amniote model systems. Unlike chick and rabbit, the murine primitive streak arises in situ by progressive initiation of EMT beginning in the posterior epiblast, without large-scale movement or convergence and extension of epiblast cells. Developmental Dynamics 241:270–283, 2012. © 2011 Wiley Periodicals, Inc.