title: Structural changes of rat mitral valve chordae tendineae during postnatal development.
abstract: OBJECTIVE
  Mitral valve chordae tendineae are an essential component for correct functioning of the human heart. The microstructural make-up of the chordae is responsible for their tensile properties, and is seen gradually to change with age. However, little is known of the maturation of chordae tendineae and their microstructure.
  
  
  METHODS
  To examine such maturation, structural changes in chordae tendineae were studied in rats at 1, 3, 7, 15 and 30 days of postnatal life, and in adult rats. Differences in the chordae microstructure of each age group were observed using light microscopy. The collagen fibril crimp period was determined using polarized light microscopy.
  
  
  RESULTS
  At day 1 after birth the chordae had yet to develop, and the lateral sides of the mitral valve leaflets were completely attached to the papillary muscles. Chordae developed through the formation of gaps in the leaflet tissue. From day 7 on, numerous chordae were seen. As the chordae matured, crimped collagen fibrils were formed and began to align in a longitudinally packed core with increasing density. The collagen fibril crimp period increased significantly with the age of the animal.
  
  
  CONCLUSIONS
  Rat chordae tendineae have yet to develop at postnatal day 1. Morphological development and microstructural maturation of the chordae are not completed until adulthood (>30 days). A further understanding of the development of mitral valve chordae tendineae will provide insight for the use of tissue-engineered chordae in surgical repair.
authors.affiliation: Center for Congenital Heart Diseases, Department of Pediatric Cardiology, Beatrix Children's Hospital, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands. m.g.dickinson@umcg.nl
authors.forename: Michael G
authors.initials: MG
authors.lastname: Dickinson
authors.forename: Ivan
authors.initials: I
authors.lastname: Vesely
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002815:Chordae Tendineae / Q000033:anatomy & histology* / Q000254:growth & development* / Q000502:physiology; D003094:Collagen / Q000502:physiology; D006801:Humans; D008859:Microscopy, Polarization; D008943:Mitral Valve / Q000033:anatomy & histology* / Q000254:growth & development* / Q000502:physiology; D009210:Myofibrils / Q000502:physiology; D010210:Papillary Muscles / Q000033:anatomy & histology* / Q000254:growth & development* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D023822:Tissue Engineering
chemical_list: D003094:Collagen