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Please cite this paper as: Wagner R, Modla S, Hossler F, Czymmek K. Three-dimensional analysis and computer modeling of the capillary endothelial vesicular system with electron tomography. Microcirculation 19: 477–484, 2012. Abstract Objective: We examined the three-dimensional organization of the endothelial vesicular system with TEM tomography of semi-thick sections. Materials and 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. |
