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Cover image: Sixth cleavage sea urchin embryo. Four large micromeres, two of which are visible (pink), produce the skeletogenic lineage. Oliveri et al., in the Feature Article on pages 5955–5962, describe the gene regulatory network that directs the fate of these cells from fourth cleavage to late blastula. Image courtesy of Andrew Ransick (California Institute of Technology, Pasadena, CA).

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April 22, 2008; 105 (16)
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