doi:10.1016/j.ydbio.2005.04.021

"Analysis of tissue flow patterns during primitive streak formation in the chick embryo".

Cheng Cui  ^a, Xuesong Yang  ^b, Manli Chuai  ^b, James A. Glazier ^a, and Cornelis J. Weijer ^{b, @} ,

^a Department of Physics, Biocomplexity Institute, Indiana University, 727 East Third Street, Swain Hall West 159, Bloomington, IN 47405-7105, USA
^b Division of Cell and Developmental Biology, Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK

^@ Corresponding author. Fax: +44 1382 345386.    e-mail:   c.j.weijer@dundee.ac.uk

We have investigated the patterns of tissue flow underlying the formation of the primitive streak in the chick embryo. Analysis of time-lapse sequences of brightfield images to extract the tissue velocity field and of fluorescence images of small groups of DiI-labelled cells have shown that epiblast cells move in two large-scale counter-rotating streams, which merge at the site of streak formation. Despite the large-scale tissue flows, individual cells appear to move little relative to their neighbours. As the streak forms, it elongates in both the anterior and posterior directions. Inhibition of actin polymerisation via local application of the inhibitor latrunculin A immediately terminates anterior extension of the streak tip, but does not prevent posterior elongation. Inhibition of actin polymerisation at the base of the streak completely inhibits streak formation, implying that continuous movement of cells into the base of the forming streak is crucial for extension. Analysis of cycling cells in the early embryo shows that cell-cycle progression in the epiblast is quite uniform before the primitive streak forms then decreases in the central epiblast and incipient streak and increases at the boundary between the area pellucida and area opaca during elongation. The cell-cycle inhibitor aphidicolin, at concentrations that completely block cell-cycle progression, permits initial streak formation but arrests development during extension. Our analysis suggests that cell division maintains the cell-flow pattern that supplies the streak with cells from the lateral epiblast, which is critical for epiblast expansion in peripheral areas, but that division does not drive streak formation or the observed tissue flow.

Keywords: Primitive streak; Cell movement; Cell proliferation; FGF signalling; Time-lapse analysis; Vector velocity field

Additional References:

1. Frenster JH, "Analysis of Queueing and Renewal Systems in Hodgkin's Disease" .

2.  Medical Systems Biology in Health and Disease

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