#tubule  a small tube
  supertype:  tube-shaped_structure__tube  (anatomy) any hollow cylindrical body structure
  subtype:  microtubule  a microscopically small tubule
  subtype:  nephron__uriniferous_tubule__uriniferoustubule  any of the small tubules that are the excretory units of the vertebrate kidney
  subtype:  seminiferous_tubule  any of the numerous long convoluted tubules in the testis which are the sites where spermatozoa mature
  subtype:  vasa_efferentia  the several highly convoluted tubules that lead from the rete testis to the vas deferens and form the head of the epididymis
  subtype:  trachea  one of the tubules forming the respiratory system of most insects and many arachnids

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