Crimp morphology in relaxed and stretched rat Achilles tendon

Marco Franchi, Milena Fini, Marilisa Quaranta, Viviana De Pasquale, Mario Raspanti, Gianluca Giavaresi, Vittoria Ottani, Alessandro Ruggeri

Research output: Contribution to journalArticlepeer-review


Fibrous extracellular matrix of tendon is considered to be an inextensible anatomical structure consisting of type I collagen fibrils arranged in parallel bundles. Under polarized light microscopy the collagen fibre bundles appear crimped with alternating dark and light transverse bands. This study describes the ultrastructure of the collagen fibrils in crimps of both relaxed and in vivo stretched rat Achilles tendon. Under polarized light microscopy crimps of relaxed Achilles tendons appear as isosceles or scalene triangles of different size. Tendon crimps observed via SEM and TEM show the single collagen fibrils that suddenly change their direction containing knots. The fibrils appear partially squeezed in the knots, bent on the same plane like bayonets, or twisted and bent. Moreover some of them lose their D-period, revealing their microfibrillar component. These particular aspects of collagen fibrils inside each tendon crimp have been termed 'fibrillar crimps'and may fulfil the same functional role. When tendon is physiologically stretched in vivo the tendon crimps decrease in number (46.7%) (P

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalJournal of Anatomy
Issue number1
Publication statusPublished - Jan 2007


  • Crimp
  • SEM
  • Stretching
  • TEM
  • Tendon

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Anatomy


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