Ultrastructural studies define soluble macromolecular, particulate, and cellular transendothelial cell pathways in venules, lymphatic vessels, and tumor‐associated microvessels in man and animals

摘要: We present de novo studies and review published efforts from our laboratory, spanning 12 years (from 1988 to 2000), where we have used ultrastructural approaches study the functional anatomy of microvasculature in man animals health disease. These defined a new endothelial cell organelle, termed vesiculo-vacuolar organelle (VVO), which participates regulated transendothelial passage soluble macromolecules. The defining this utilized ultrathin serial sections, three-dimensional computer-assisted reconstructions, electron-dense tracers establish luminal abluminal continuity VVOs. Commonality VVOs caveolae is suggested by individual units caveolae, presence caveolin both structures, mathematical analysis morphometric data, all suggest that form fusions size equivalent vesicles caveolar size. Ultrastructural localized potent permeability factors their specific receptors vivo tumor allergic inflammation models. Regulation through has been quantified shown be increased microvessels control vessels exposed permeability-inducing mediators. particulate macromolecules occurs vacuolar transport vessels; factor-exposed vessels, colloidal carbon traversed cells via development pores did not communicate with or disrupt intercellular junctions gap formation. Serial section reconstructions established these findings possible sectioning samples an acute model revealed traffic route for motile neutrophils platelets absence classical criteria secretion either cell. Microsc. Res. Tech. 57:289–326, 2002. © 2002 Wiley-Liss, Inc.