Electron microscopy of endothelial microvilli of large arteries

Fujimoto, Sunao; Yamamoto, Kōji; Takeshige, Yoshio

doi:10.1002/ar.1091830204

Cited by 21 publications

(11 citation statements)

References 11 publications

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“…Several types of membrane projections have been described for endothelial cells 8 22 23 24 , and indeed, RANTES as well as IL-8/CXCL8 have been detected on microvillous-like extensions on the luminal endothelial cell surface 8 . We therefore asked whether RANTES filaments are associated with membrane projections in HUVECs.…”

Section: Resultsmentioning

confidence: 99%

“…During the initial events of leukocyte extravasation, membrane projections would probably increase the accessibility of the endothelium towards that of the leukocyte. Luminal endothelial membrane projections have been given names such as microfolds, microvilli, filopodia, protrusions, and nanotubes 8 22 23 24 , and some of these are likely different structures with distinct functions. Similar to what was recently reported 24 , we observed long membrane projections lateral to the endothelial cell surface as well as shorter membrane projections.…”

Section: Discussionmentioning

confidence: 99%

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Oligomerized, filamentous surface presentation of RANTES/CCL5 on vascular endothelial cells

Øynebråten

Barois

Bergeland

et al. 2015

Sci Rep

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Vascular endothelial cells present luminal chemokines that arrest rolling leukocytes by activating integrins. It appears that several chemokines must form higher-order oligomers to elicit proper in vivo effects, as mutants restricted to forming dimers have lost the ability to recruit leukocytes to sites of inflammation. Here, we show for the first time that the chemokine RANTES/CCL5 binds to the surface of human endothelial cells in a regular filamentous pattern. Furthermore, the filaments bound to the surface in a heparan sulfate-dependent manner. By electron microscopy we observed labeling for RANTES on membrane projections as well as on the remaining plasma membrane. Mutant constructs of RANTES restricted either in binding to heparin, or in forming dimers or tetramers, appeared either in a granular, non-filamentous pattern or were not detectable on the cell surface. The RANTES filaments were also present after exposure to flow, suggesting that they can be present in vivo. Taken together with the lacking in vivo or in vitro effects of RANTES mutants, we suggest that the filamentous structures of RANTES may be of physiological importance in leukocyte recruitment.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Oligomerized, filamentous surface presentation of RANTES/CCL5 on vascular endothelial cells

Øynebråten

Barois

Bergeland

et al. 2015

Sci Rep

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“…They have been interpreted by these authors as originating from endothelial cells in the process of intraluminal migration. Although intraluminal projections are also present in adult endothelium, they are claimed to be particularly prominent in developing vessels (Fujimoto et al 1975;Wagner 1980). Whether such intraluminal endothelial cell processes do really initiate pillar formation remains an open question.…”

Section: Discussionmentioning

confidence: 99%

Evidence for intussusceptive capillary growth in the chicken chorio-allantoic membrane (CAM)

1993

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The aim of our investigations was to test whether the chicken chorio-allantoic membrane (CAM) could be an adequate in vivo model for a new mode of capillary growth, originally described in the rat lung and termed intussusceptive microvascular growth. According to that concept the capillary system does not grow by sprouting of vessels, but expands by insertion of transcapillary tissue pillars or posts which form new intercapillary meshes. In the present study, we observed slender transcapillary tissue pillars with diameters around 1 microns in the CAM by in vivo microscopy, and analyzed their ultrastructure by transmission electron microscopic investigation of serial sections. The pillars corresponded in size to those previously described in rat lung microvasculature. On day 7, the pillar core contained endothelial-, endothelial-like cells and collagen fibers, and on day 12 additionally chorionic epithelial cells. As a hypothesis we propose that slender cytoplasmic extensions of endothelial cells, heavily interdigitated in the post area and often projecting into the vascular lumen, could initiate the first step of pillar formation, i.e., interconnect opposite capillary walls. During both stages of development endothelial-like cells were observed in close relationship with the pillars. These cells seem to be relevant for tissue post completion and growth, as they were found to invade the core of the pillars. From the localization of the interendothelial junctions in the post region, a certain similarity to the concept proposed for the lung can be found. The observations confirm that the CAM is a very suitable material for the in vivo investigation of intussusceptive capillary growth.

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“…1977], rabbit aorta [Tokunaga et al. 1973;Fujimoto et al, 1975], and human fetal aorta, pulmonary artery, and ductus arteriosus [Fujimoto et al. 1975], were not seen in our specimens.…”

Section: Discussionmentioning

confidence: 56%

Scanning Electron Microscopy of Pulmonary Vascular Endothelium in Rats with Hypoxia-Induced Hypertension

Hung¹,

McKenzie²,

Mattioli³

et al. 1986

Cells Tissues Organs

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Scanning electron microscopy was used to study the endothelial surface of the pulmonary trunk, artery, and vein in normobaric control rats as well as in rats exposed to hypobaric hypoxia for 7 and 21 days. The individual endothelial cells of the normobaric pulmonary trunk and hilar artery were flat and slightly elongated with elevated nuclear regions, and those of the intermediate-sized artery were more elongated and had more microvilli than the large arteries studied. Their endothelial cell boundaries were outlined by beaded cytoplasmic projections. The surfaces of the normobaric hilar and intermediate-sized veins were smooth and demonstrated numerous longitudinal streaks. These venous endothelial cells were elongated and their cell boundaries were outlined by low discontinuous marginal folds. Exposure to hypobaric hypoxia caused the following changes on the arterial surface: elevation of the endothelial cells; formation of microvilli-rich cell clusters; formation of hollow defects; and the attachment of leukocytes. Hypobaric hypoxia also caused the disappearance of the longitudinal streaks and the occurrence of microvilli-rich cells in the hilar veins. The endothelial surface modifications in the hypobaric rats could be related to thickening of the endothelium, intimal edema, increased intimal connective tissue, luminal invasion of leukocytes, and increased endothelial cell proliferation, known to occur in systemic arteries of hypertensive animals.

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Electron microscopy of endothelial microvilli of large arteries

Cited by 21 publications

References 11 publications

Oligomerized, filamentous surface presentation of RANTES/CCL5 on vascular endothelial cells

Oligomerized, filamentous surface presentation of RANTES/CCL5 on vascular endothelial cells

Evidence for intussusceptive capillary growth in the chicken chorio-allantoic membrane (CAM)

Scanning Electron Microscopy of Pulmonary Vascular Endothelium in Rats with Hypoxia-Induced Hypertension

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