Three-dimensional visualization of testis cord morphogenesis, a novel tubulogenic mechanism in development

Authors

  • Alexander N. Combes,

    1. Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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  • Emmanuelle Lesieur,

    1. Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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  • Vincent R. Harley,

    1. Prince Henry's Institute of Medical Research, Melbourne, Australia
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  • Andrew H. Sinclair,

    1. Murdoch Children's Research Institute, and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia
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  • Melissa H. Little,

    1. Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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  • Dagmar Wilhelm,

    1. Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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  • Peter Koopman

    Corresponding author
    1. Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
    • Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
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Abstract

Testis cords are specialized tubes essential for generation and export of sperm, yet the mechanisms directing their formation, and the regulation of their position, size, shape, and number remain unclear. Here, we use a novel fluorescence-based three-dimensional modeling approach to show that cords initially form as a network of irregular cell clusters that are subsequently remodeled to form regular parallel loops, joined by a flattened plexus at the mesonephric side. Variation in cord number and structure demonstrates that cord specification is not stereotypic, although cord alignment and diameter becomes relatively consistent, implicating compensatory growth mechanisms. Branched, fused, and internalized cords were commonly observed. We conclude that the tubule-like structure of testis cords arise through a novel form of morphogenesis consisting of coalescence, partitioning, and remodeling. The methods we describe are applicable to investigating defects in testis cord development in mouse models, and more broadly, studying morphogenesis of other tissues. Developmental Dynamics 238:1033–1041, 2009. © 2009 Wiley-Liss, Inc.

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