title: [Ultrastructural study of the pulmonary veins in pigs].
abstract: OBJECTIVE
  To explore the possible relationship between the ultrastructural characteristics of pulmonary veins and the pathogenesis of atrial fibrillation originating from pulmonary veins.
  
  
  METHODS
  The pulmonary veins from domestic pigs were serially sectioned (2 mm) transversely along the vessels. The odd number sections were fixed in 10% phosphate buffered formalin solution and the even number sections were fixed in 3% Glutaral for further electron microscopy observations.
  
  
  RESULTS
  Two cell types were found in the pulmonary veins of pigs. One cell type was the P-like cells that had an empty-appearing cytoplasm containing only sparse myofibrils and small mitochondria, both of which were randomly distributed. Another cell type was slender transitional cells with plenty of longitudinally displayed myofibrils.
  
  
  CONCLUSIONS
  P-like cells in the pig pulmonary veins were found using electron microscopy in this study and ectopic beats from P-like cells in the myocardial sleeves in the pulmonary veins might be responsible for atrial fibrillation originating from pulmonary veins.
authors.affiliation: Department of Cardiology, General Hospital of PLA, Beijing 100853, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Yu-tang
authors.initials: YT
authors.lastname: Wang
authors.forename: Zhao-liang
authors.initials: ZL
authors.lastname: Shan
authors.forename: Jun
authors.initials: J
authors.lastname: Yi
authors.forename: Xiang-min
authors.initials: XM
authors.lastname: Shi
mesh_terms: D000818:Animals; D008854:Microscopy, Electron; D032383:Myocytes, Cardiac / Q000648:ultrastructure*; D011667:Pulmonary Veins / Q000648:ultrastructure*; D013552:Swine