Time to make the doughnuts: Building and shaping seamless tubes

Semin Cell Dev Biol. 2017 Jul;67:123-131. doi: 10.1016/j.semcdb.2016.05.006. Epub 2016 May 10.


A seamless tube is a very narrow-bore tube that is composed of a single cell with an intracellular lumen and no adherens or tight junctions along its length. Many capillaries in the vertebrate vascular system are seamless tubes. Seamless tubes also are found in invertebrate organs, including the Drosophila trachea and the Caenorhabditis elegans excretory system. Seamless tube cells can be less than a micron in diameter, and they can adopt very simple "doughnut-like" shapes or very complex, branched shapes comparable to those of neurons. The unusual topology and varied shapes of seamless tubes raise many basic cell biological questions about how cells form and maintain such structures. The prevalence of seamless tubes in the vascular system means that answering such questions has significant relevance to human health. In this review, we describe selected examples of seamless tubes in animals and discuss current models for how seamless tubes develop and are shaped, focusing particularly on insights that have come from recent studies in Drosophila and C. elegans.

Keywords: Capillary; Excretory system; Seamless tube; Trachea.

Publication types

  • Review
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / growth & development
  • Caenorhabditis elegans / metabolism
  • Capillaries / anatomy & histology
  • Capillaries / cytology*
  • Capillaries / metabolism
  • Cell Polarity
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / growth & development
  • Drosophila melanogaster / metabolism
  • Endothelial Cells / metabolism
  • Endothelial Cells / ultrastructure*
  • Epithelial Cells / metabolism
  • Epithelial Cells / ultrastructure*
  • Exocytosis
  • Gene Expression Regulation
  • Humans
  • Models, Biological
  • Morphogenesis / genetics*
  • Pinocytosis
  • Trachea / anatomy & histology
  • Trachea / cytology*
  • Trachea / metabolism
  • Vascular Diseases / genetics
  • Vascular Diseases / metabolism
  • Vascular Diseases / pathology*


  • Cytoskeletal Proteins