title: Three-dimensional analysis and computer modeling of the capillary endothelial vesicular system with electron tomography.
abstract: OBJECTIVE
  We examined the three-dimensional organization of the endothelial vesicular system with TEM tomography of semi-thick sections.
  
  
  METHODS
  Mouse abdominal muscle capillaries were perfused with terbium to label vesicular compartments open to the luminal surface. The tissue was prepared for TEM and semi-thick (250 nm) sections were cut. Dual axis tilt series, collected from +60° to -60° at 1° increments, were acquired in regions of labeled abluminal caveolae. These tomograms were reconstructed and analyzed to reveal three-dimensional vesicular associations not evident in thin sections.
  
  
  RESULTS
  Reconstructed tomograms revealed free vesicles, both labeled and unlabeled, in the endothelial cytoplasm as well as transendothelial channels that spanned the luminal and abluminal membranes. A large membranous compartment connecting the luminal and abluminal surfaces was also present. Computer modeling of tomographic data and video animations provided three-dimensional perspectives to these structures.
  
  
  CONCLUSIONS
  Uncertainties associated with other three-dimensional methods to study the capillary wall are remedied by tomographic analysis of semi-thick sections. Transendothelial channels of fused vesicles and free cytoplasmic vesicles give credence to their role as large pores in the transport of solutes across the walls of continuous capillaries.
authors.affiliation: Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, USA. rags@udel.edu
authors.forename: Roger
authors.initials: R
authors.lastname: Wagner
authors.forename: Shannon
authors.initials: S
authors.lastname: Modla
authors.forename: Fred
authors.initials: F
authors.lastname: Hossler
authors.forename: Kirk
authors.initials: K
authors.lastname: Czymmek
mesh_terms: D000818:Animals; D002196:Capillaries / Q000648:ultrastructure*; D022162:Cytoplasmic Vesicles / Q000648:ultrastructure*; D055032:Electron Microscope Tomography; D004730:Endothelium, Vascular / Q000648:ultrastructure*; D021621:Imaging, Three-Dimensional; D051379:Mice; D018482:Muscle, Skeletal / Q000098:blood supply / Q000648:ultrastructure; D013725:Terbium / Q000494:pharmacology
chemical_list: D013725:Terbium