the ecm moves during primitive streak formation—computation of ecm versus cellular motionecm移动在原条formation-computation ecm和细胞运动.pdfVIP

PLoS BIOLOGY The ECM Moves during Primitive Streak Formation—Computation of ECM Versus Cellular Motion ¤ * Evan A. Zamir , Brenda J. Rongish, Charles D. Little Department of Anatomy and Cell Biology, School of Medicine, The University of Kansas Medical Center, Kansas City, Kansas, United States of America Galileo described the concept of motion relativity—motion with respect to a reference frame—in 1632. He noted that a person below deck would be unable to discern whether the boat was moving. Embryologists, while recognizing that embryonic tissues undergo large-scale deformations, have failed to account for relative motion when analyzing cell motility data. A century of scientific articles has advanced the concept that embryonic cells move (‘‘migrate’’) in an autonomous fashion such that, as time progresses, the cells and their progeny assemble an embryo. In sharp contrast, the motion of the surrounding extracellular matrix scaffold has been largely ignored/overlooked. We developed computational/optical methods that measure the extent embryonic cells move relative to the extracellular matrix. Our time-lapse data show that epiblastic cells largely move in concert with a sub-epiblastic extracellular matrix during stages 2 and 3 in primitive streak quail embryos. In other words, there is little cellular motion relative to the extracellular matrix scaffold—both components move together as a tissue. The extracellular matrix displacements exhibit bilateral vortical motion, convergence to the midline, and extension along the presumptive vertebral axis—all patterns previously attributed solely to cellular ‘‘migration.’’ Our time-resolved data pose ne