| During vertebrate embryonic development, the body segments are formed in a periodic and sequential process controlled by a biological clock. This clock comprises a population of cells that contain autonomous genetic oscillators. Individual oscillators are coupled to neighbors in order to produce a reliable rhythm that results in a precise segmented pattern. Intercellular communication involves a complex cascade of events that introduces time delays in the coupling. Remarkably, these time delays are comparable to the period of oscillations itself, and consequently cannot be neglected in this particular system. We develop a generic description of the segmentation clock, using phase oscillators coupled with a time delay. The theory predicts that delayed coupling regulates the period of the segmentation clock. These predictions have been verified in zebrafish embryos in which the coupling has been altered. |
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