Progressive Bundling of Fibrillin Microfibrils into Oxytalan Fibers in the Chick Presumptive Dermis

Authors

  • Keizo Shinozuka,

    1. Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan
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    • Keizo Shinozuka and Yosuke Yamazaki contributed equally to this work.

  • Yosuke Yamazaki,

    1. Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan
    2. Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
    3. Department of Oral Structure and Function, Nihon University Graduate School of Dentistry, Tokyo, Japan
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    • Keizo Shinozuka and Yosuke Yamazaki contributed equally to this work.

  • Maki Yuguchi,

    1. Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan
    2. Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
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  • Taku Toriumi,

    1. Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan
    2. Department of Oral Structure and Function, Nihon University Graduate School of Dentistry, Tokyo, Japan
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  • Rie Suzuki,

    1. Department of Oral Structure and Function, Nihon University Graduate School of Dentistry, Tokyo, Japan
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  • Eichi Tsuruga,

    1. Section of Functional Structure, Department of Morphological Biology, Division of Biomedical Sciences, Fukuoka Dental College, Fukuoka, Japan
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  • Keitaro Isokawa

    Corresponding author
    1. Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan
    2. Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
    3. Department of Oral Structure and Function, Nihon University Graduate School of Dentistry, Tokyo, Japan
    • Department of Anatomy, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
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    • Fax: +81-3-3295-8783


Abstract

Dorsoventral fibers in the presumptive dermis of the chick limb bud reported first by Hurle's group in 1989 are now revealed as bundles of fibrillin microfibrils (Isokawa et al., 2004). The bundles, which could be called oxytalan fibers at the light microscopic level, are aligned perpendicularly to the overlying ectoderm and form a unique fiber array, originating directly from the basal lamina. This well-oriented organization is beneficial in examining the process of in vivo bundling of microfibrils into oxytalan fibers. In this study, sections through the presumptive limb dermis were preferentially prepared from chick embryos at Days 4–6 (ED4-6). Immunohistochemically, fibrillin-positive dots representing cross-sectioned surfaces of individual fibers, increased in size from ED4 to 6, but their number per unit area remained constant. Ultrastructurally, a single oxytalan fiber at ED4 consisted of ∼15 microfibrils; the latter number increased fourfold from ED4 to 5 and threefold from ED5 to 6. Oxytalan fibers were all closely associated with mesenchymal cell; notably, the fibers at ED5 and 6 were held in a shallow ditch on the cell body or by lamellipodial cytoplasmic protrusion. In the sites of cell–fiber adhesion, microfibrils in the periphery of an oxytalan fiber appeared to adhere directly or by means of short flocculent strands to a nearby cell membrane; the latter showed a thickening of plasmalemma and its undercoat, indicating the presence of adhesive membrane specification. These findings suggest that the bundling of microfibrils is a progressive and closely cell-associated process. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.

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