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The Vesiculo–Vacuolar Organelle (VVO): A New Endothelial Cell Permeability Organelle

The Vesiculo–Vacuolar Organelle (VVO): A New Endothelial Cell Permeability Organelle A newly defined endothelial cell permeability structure, termed the Vesiculo–Vacuolar organelle (VVO), has been identified in the microvasculature that accompanies tumors, in venules associated with allergic inflammation, and in the endothelia of normal venules. This organelle provides the major route of extravasation of macromolecules at sites of increased vascular permeability induced by vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), serotonin, and histamine in animal models. Continuity of these large sessile structures between the vascular lumen and the extracellular space has been demonstrated in kinetic studies with ultrastructural electron-dense tracers, by direct observation of tilted electron micrographs, and by ultrathin serial sections with three-dimensional computer reconstructions. Ultrastructural enzyme-affinity cytochemical and immunocytochemical studies have identified histamine and VPF/VEGF bound to VVOs in vivo in animal models in which these mediators of permeability are released from mast cells and tumor cells, respectively. The high-affinity receptor for VPF/VEGF, VEGFR-2, was localized to VVOs and their substructural components by pre-embedding ultrastructural immunonanogold and immunoperoxidase techniques. Similar methods were used to localize caveolin and vesicle-associated membrane protein (VAMP) to VVOs and caveolae, indicating a possible commonality of formation and function of VVOs to caveolae. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Histochemistry & Cytochemistry SAGE

The Vesiculo–Vacuolar Organelle (VVO): A New Endothelial Cell Permeability Organelle

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References (67)

Publisher
SAGE
Copyright
© 2001 Authors
ISSN
0022-1554
eISSN
1551-5044
DOI
10.1177/002215540104900401
pmid
11259444
Publisher site
See Article on Publisher Site

Abstract

A newly defined endothelial cell permeability structure, termed the Vesiculo–Vacuolar organelle (VVO), has been identified in the microvasculature that accompanies tumors, in venules associated with allergic inflammation, and in the endothelia of normal venules. This organelle provides the major route of extravasation of macromolecules at sites of increased vascular permeability induced by vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), serotonin, and histamine in animal models. Continuity of these large sessile structures between the vascular lumen and the extracellular space has been demonstrated in kinetic studies with ultrastructural electron-dense tracers, by direct observation of tilted electron micrographs, and by ultrathin serial sections with three-dimensional computer reconstructions. Ultrastructural enzyme-affinity cytochemical and immunocytochemical studies have identified histamine and VPF/VEGF bound to VVOs in vivo in animal models in which these mediators of permeability are released from mast cells and tumor cells, respectively. The high-affinity receptor for VPF/VEGF, VEGFR-2, was localized to VVOs and their substructural components by pre-embedding ultrastructural immunonanogold and immunoperoxidase techniques. Similar methods were used to localize caveolin and vesicle-associated membrane protein (VAMP) to VVOs and caveolae, indicating a possible commonality of formation and function of VVOs to caveolae.

Journal

Journal of Histochemistry & Cytochemistry – SAGE

Published: Apr 1, 2001

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