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Dynamics of thin filopodia during sea urchin gastrulation

Miller, Jeffrey and Fraser, Scott E. and McClay, David (1995) Dynamics of thin filopodia during sea urchin gastrulation. Development, 121 (8). pp. 2501-2511. ISSN 0950-1991.

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At gastrulation in the sea urchin embryo, a dramatic rearrangement of cells establishes the three germ layers of the organism. Experiments have revealed a number of cell interactions at this stage that transfer patterning information from cell to cell. Of particular significance, primary mesenchyme cells, which are responsible for production of the embryonic skeleton, have been shown to obtain extensive positional information from the embryonic ectoderm. In the present study, high resolution Nomarski imaging reveals the presence of very thin filopodia (02-0.4 micron in diameter) extending from primary mesenchyme cells as well as from ectodermal and secondary mesenchyme cells. These thin filopodia sometimes extend to more than 80 microns in length and show average growth and retraction rates of nearly 10 microns/minute. The filopodia are highly dynamic, rapidly changing from extension to resorption; frequently, the resorption changes to resumption of assembly. The behavior, location and timing of active thin filopodial movements does not correlate with cell locomotion; instead, there is a strong correlation suggesting their involvement in cell-cell interactions associated with signaling and patterning at gastrulation. Nickel-treatment, which is known to create a patterning defect in skeletogenesis due to alterations in the ectoderm, alters the normal position-dependent differences in the thin filopodia. The effect is present in recombinant embryos in which the ectoderm alone was treated with nickel, and is absent in recombinant embryos in which only the primary mesenchyme cells were treated, suggesting that the filopodial length is substratum dependent rather than being primary mesenchyme cell autonomous. The thin filopodia provide a means by which cells can contact others several cell diameters away, suggesting that some of the signaling previously thought to be mediated by diffusible signals may instead by the result of direct receptor-ligand interactions between cell membranes.

Item Type:Article
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Fraser, Scott E.0000-0002-5377-0223
Additional Information:© 1995 Company of Biologists Limited. Accepted 20 May 1995. This collaboration grew from observations that were made during the Embryology Course at the Marine Biological Laboratory, Woods Hole. The authors appreciate the input from the students and faculty of that course. This work was supported by NIH grant HD14483 to DRM and by NIMH Silvio Conti Center grant MH49176 to SF.
Funding AgencyGrant Number
National Institute of Mental Health (NIMH)MH49176
Subject Keywords:primary mesenchyme; secondary mesenchyme; cell interactions; videoimaging; nerve growth cone; sea urchin
Issue or Number:8
Record Number:CaltechAUTHORS:20120216-102445717
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29334
Deposited On:17 Feb 2012 21:18
Last Modified:03 Oct 2019 03:40

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