View source for File:Critical stages of the development of the primitive streak in the chick embryo..png

==Critical stages of the development of the primitive streak in the chick embryo.==
Wnt 8c expression during formation of Koller's sickle and the primitive streak. (A, B) At stage HH1 [39] Wnt8c (A) and Chordin (B) RNAs are expressed in the Area Opaca. At this time the embryo is growing and the epiblast increases in size as shown by the outward-pointing velocity arrows (C). At stage HH2, Wnt8c (D) and Chordin (E) RNA are both expressed along the primitive streak, but the cell flow patterns have changed to two counter-rotating cells flows (F). At stage HH4, Wnt8c (G) is expressed in the base of the streak, while Chordin RNA is expressing in the tip of the streak and the surrounding forming neural plate (H). During this phase the large-scale rotational movements start to transform into flows along the anterior-posterior axis of elongation of the embryo (I). AO Area Opaca, AP Area Pellucida, black arrow tip of the streak, red arrow base of the streak. In the velocity flow fields the thick horizontal white bar indicates cell flow speeds of 1 µm/min. Images C, F and I were taken at t = 0 minutes, t = 300 minutes and t = 800 minutes from the start of the experiment at HH1. 

==References==
<references/>
Vasiev B, Balter A, Chaplain M, Glazier JA, Weijer CJ (2010) '''Modeling Gastrulation in the Chick Embryo: Formation of the Primitive Streak.'''  PLoS ONE 5(5): e10571. doi:10.1371/journal.pone.0010571

Copyright: © 2010 Vasiev et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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