Gastrulation in the spider Zygiella x-notata involves three distinct phases of cell internalization

Authors

  • R. Crystal Chaw,

    1. Kleinholtz Biological Laboratories, Department of Biology, Reed College, Portland, Oregon
    Current affiliation:
    1. Department of Integrative Biology, University of California, Berkeley, CA 94720
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    • Drs. Chaw and Vance contributed equally to this work.

  • Emily Vance,

    1. Kleinholtz Biological Laboratories, Department of Biology, Reed College, Portland, Oregon
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    • Drs. Chaw and Vance contributed equally to this work.

  • Steven D. Black

    Corresponding author
    1. Kleinholtz Biological Laboratories, Department of Biology, Reed College, Portland, Oregon
    • Kleinholtz Biological Laboratories, Department of Biology, Reed College, 3203 S.E. Woodstock Blvd., Portland, OR 97202
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Abstract

The cell movements of gastrulation were analyzed in embryos of the spider Zygiella x-notata, using time-lapse video, cell tracing, and improved histology. Cells are internalized near the center of the germ disc in three distinct phases. First, cumulus mesenchyme cells ingress and migrate as a group beneath the superficial layer. Second, mass internalization through a blastopore yields a diffusely organized deep layer. Third, superficial cells accumulate at the center of the germ disc to form the caudal bud. The floor is internalized, and the caudal bud moves over the nascent dorsal field to form the caudal lobe. This pattern of gastrulation differs from the canonical pattern described in the historical literature: (1) the cumulus of Z. x-notata is completely formed before any other cells internalize; and (2) the caudal lobe is formed by means of the caudal bud, which is a locus of cell internalization. Developmental Dynamics 236:3484–3495, 2007. © 2007 Wiley-Liss, Inc.

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