Fibrinolysis in Decidual Spiral Arteries in Late Pregnancy

1978 ◽  
Vol 39 (03) ◽  
pp. 751-758 ◽  
Author(s):  
B L Sheppard ◽  
J Bonnar
Keyword(s):  
Electron Microscopy ◽  
Endothelial Cells ◽  
Fibrinolytic Activity ◽  
Physiological Mechanism ◽  
Late Pregnancy ◽  
Full Term ◽  
Fibrin Deposition ◽  
Placental Villi ◽  
The Media ◽  
Slide Technique

SummaryThe fibrinolytic activity of the intimal cells of decidual spiral arteries and the syncytium of placental villi was studied by electron microscopy in ten normal full-term human pregnancies using a modification of the fibrin slide technique. Endothelial cells lining the intima of the decidual spiral arteries showed a considerably greater fibrinolytic activity than intimal cytotrophoblast and the syncytiotrophoblast showed no activity.The replacement of endothelial cells by an intimal lining of cytotrophoblast, and the presence of cytotrophoblast in the media, appears to play an important role in the reduction of the fibrinolytic activity of the vessel. This inhibition of fibrinolytic activity in the utero-placental arteries may be the physiological mechanism which controls fibrin deposition in these vessels and on the placental villi.

Study of Haemostasis in Schoenlein-Henoch’s Syndrome

1975 ◽  
Author(s):  
Gy. Boros ◽  
J. Sámik ◽  
Ljubov Gofman ◽  
Judit Nagv ◽  
Gy. Deák ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Blood Coagulation ◽  
Fibrinolytic Activity ◽  
Capillary Permeability ◽  
Thrombin Time ◽  
Consumption Coagulopathy ◽  
Fibrin Deposition ◽  
Coagulation Defect ◽  
Capillary Resistance

Blood coagulation, thrombocyte function and capillary resistance were studied in 21 adult patients with Schoenlein-Henoch’s syndrome. 20 different tests were carried out at different stages of the disease. In 2 cases skin, in 1 mesocolon and in 10 kidneys were examined histologicaly (light microscopy, immunofluorescence, electron microscopy).Capillary permeability was increased at least once in every patient. All patients but 2 were characterized by hypercoagulability. In addition to thrombotic changes, an increase in labile fibrinogen was detected in the serum of 12 patients, and thrombin time was prolonged in 11 patients on 31 occasions. Plasma fibrinolytic activity was increased in 11 patients. Fibrin deposition was demonstrable in the skin of 2 in the mesocolon of 1 and in the kidneys of 7 patients.It is suggested that besides the capillaropathy a coagulation defect, resembling consumption coagulopathy is a characteristic of Schoenlein-Henoch’s syndrome.

3D imaging of full-term human placental villi by serial block face-scanning electron microscopy

Placenta ◽  
2017 ◽  
Vol 59 ◽  
pp. 175-176
Author(s):  
Haruhiko Shimada ◽  
Yuuki Yamaguchi ◽  
Takami Takizawa ◽  
Hironori Takahashi ◽  
Akihid Ohkuchi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
3D Imaging ◽  
Full Term ◽  
Face Scanning ◽  
Placental Villi ◽  
Block Face ◽  
Scanning Electron

Venous Stasis - Effect On Release Of Plasminogen Activators

1981 ◽  
Author(s):  
B Risberg ◽  
A Bylock ◽  
T Kjellström ◽  
B Stenberg
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Endothelial Cells ◽  
Fibrinolytic Activity ◽  
Vessel Wall ◽  
Plasminogen Activators ◽  
Venous Stasis ◽  
Functional Changes ◽  
Structural Deterioration ◽  
Scanning Electron

Venous stasis affects the fibrinolytic system. This is clinically utilized in the stasis test. Regional increase in fibrinolytic activity is found in the blood. By what mechanism the fibrinolytic activators are released is not known. It was the purpose of the present investigation to study the morphological and functional changes in the vessel wall after venous stasis.Methods: The infrarenal cavai vein in rats was occluded by a ligature. Biopsies were taken at different intervals from 2 to 8 hours after ligation. Morphological changes were studied with scanning electron microscopy. Tissue fibrinolytic activity was examined histochemically.Results: Stasis was followed by a progressive decrease in plasminogen activator activity in the intimai layer of the vessel wall. At 8 h the decrease was pronounced and the activity significantly lower than control values. The fibrinolytic activity in the adventitial layer was not influenced by stasis. The scanning electron microscopy studies demonstrated a progressive morphological change with destruction of the endothelial cells.Conclusions: Venous stasis was followed by progressive structural deterioration of the endothelial cells with release of plasminogen activators. Cellular degeneration might be responsible for enhanced release of activators during stasis.

The Role of Platelets and Fibrin in Uteroplacental Arteries in Normal Human Pregancy

1979 ◽  
Author(s):  
B.I. Sheppard ◽  
J. Bonnar
Keyword(s):  
Blood Flow ◽  
Late Pregnancy ◽  
Normal Pregnancy ◽  
Artery Occlusion ◽  
Trophoblast Invasion ◽  
Fibrin Deposition ◽  
Trophoblast Cells ◽  
Structural Support ◽  
The Media ◽  
Normal Human

In normal human pregnancy the uteroplacental vessels undergo extensive morphological adaptations to provide an increasing blood flow to the placenta. These involve platelets and fibrin adjacent to trophoblast invasion of spiral arteries.In early pregnancy, single layers of platelets or small thrombi are seen between trophoblast cells which form a pseudo-endothelium of the spiral arteries. In the media trophoblast cells and fibrin are present in an amorphous matrix which replaces the musculo-elastic component of the vessel. In late pregnancy these vascular changes extend into the myometrium, fibrin deposition is increased and mature mural thrombi are found.The fibrin deposition in uteroplacental arteries, is a physiological phenoncma of pregnancy. Fibrin may provide the dynamic structural support required in these vessels expanding to accommodate an increasing blood flow. Fibrin also enables the immediate collapse of the vessel following placental separation. Mural thrombosis in the arterial supplyprobably accounts for areas of ischemia and small placental infarcts found in normal pregnancy. Because of the large placental reserve, this minor degree of spiral artery occlusion does not appear to effect adversely the fetus.

Complex Vesicles, Microtubules, and Cytoplasmic Filaments in the Endothelial Cells of Normal Dog Aorta

1968 ◽  
Vol 26 ◽  
pp. 172-173
Author(s):  
C. N. Sun ◽  
J. J. Ghidoni
Keyword(s):  
Electron Microscopy ◽  
Endothelial Cells ◽  
Cross Sections ◽  
Functional Significance ◽  
Tubular Structures ◽  
Aldehyde Fixation ◽  
Cytoplasmic Filaments

Endothelial cells in longitudinal and cross sections of aortas from 3 randomly selected “normal” mongrel dogs were studied by electron microscopy. Segments of aorta were distended with cold cacodylate buffered 5% glutaraldehyde for 10 minutes prior to being cut into small, well oriented tissue blocks. After an additional 1-1/2 hour period in glutaraldehyde, the tissue blocks were well rinsed in buffer and post-fixed in OsO4. After dehydration they were embedded in a mixture of Maraglas, D.E.R. 732, and DDSA.Aldehyde fixation preserves the filamentous and tubular structures (300 Å and less) for adequate demonstration and study. The functional significance of filaments and microtubules has been recently discussed by Buckley and Porter; the precise roles of these cytoplasmic components remains problematic. Endothelial cells in canine aortas contained an abundance of both types of structures.

Fibrinolytic Activity of Human Veins in Arms and Legs

1968 ◽  
Vol 20 (01/02) ◽  
pp. 247-256 ◽  
Author(s):  
M Pandolfi ◽  
B Robertson ◽  
S Isacson ◽  
Inga Marie Nilsson
Keyword(s):  
Saphenous Vein ◽  
Fibrinolytic Activity ◽  
Great Saphenous Vein ◽  
Normal Subjects ◽  
Vasa Vasorum ◽  
Tissue Sections ◽  
Below The Knee ◽  
The Media

SummaryA modification of the fibrin slide method of Todd permitting a semiquantitative estimation of the fibrinolytic activity in tissue sections is described. By means of this technique, the authors have studied the fibrinolytic activity of the great saphenous vein and of superficial veins of the arm and leg in patients suffering from varices and in normal subjects. It was found that:1. Fibrinolytic activity is localized, in these vessels, mainly to the vasa vasorum of the adventitia. The media is moderately active. Intimal cells are active only when detached.2. The great saphenous vein is more active above than below the knee.3. The veins of the arm are definitely more active than the veins of the leg.4. The activator of plasminogen demonstrated in the sections by the fibrin slide method is a fairly stable enzyme still active after exposure to 60° C and resistent to moderate variations of pH.

Neutrophil Derived Cathepsin G Induces Potentially Thrombogenic Changes in Human Endothelial Cells: a Scanning Electron Microscopy Study in Static and Dynamic Conditions

1994 ◽  
Vol 72 (01) ◽  
pp. 140-145 ◽  
Author(s):  
Valeri Kolpakov ◽  
Maria Cristina D'Adamo ◽  
Lorena Salvatore ◽  
Concetta Amore ◽  
Alexander Mironov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Thrombus Formation ◽  
Cathepsin G ◽  
Arterial Segment ◽  
Dynamic Conditions ◽  
Activated Neutrophils ◽  
Scanning Electron

SummaryActivated neutrophils may promote thrombus formation by releasing proteases which may activate platelets, impair the fibrinolytic balance and injure the endothelial monolayer.We have investigated the morphological correlates of damage induced by activated neutrophils on the vascular wall, in particular the vascular injury induced by released cathepsin G in both static and dynamic conditions.Human umbilical vein endothelial cells were studied both in a cell culture system and in a model of perfused umbilical veins. At scanning electron microscopy, progressive alterations of the cell monolayer resulted in cell contraction, disruption of the intercellular contacts, formation of gaps and cell detachment.Contraction was associated with shape change of the endothelial cells, that appeared star-like, while the underlying extracellular matrix, a potentially thrombogenic surface, was exposed. Comparable cellular response was observed in an “in vivo” model of perfused rat arterial segment. Interestingly, cathepsin G was active at lower concentrations in perfused vessels than in culture systems. Restoration of blood flow in the arterial segment previously damaged by cathepsin G caused adhesion and spreading of platelets on the surface of the exposed extracellular matrix. The subsequent deposition of a fibrin network among adherent platelets, could be at least partially ascribed to the inhibition by cathepsin G of the vascular fibrinolytic potential.This study supports the suggestion that the release of cathepsin G by activated neutrophils, f.i. during inflammation, may contribute to thrombus formation by inducing extensive vascular damage.

Localization of Fibrinolytic Activators and Inhibitors in Normal and Atherosclerotic Vessels

1996 ◽  
Vol 75 (06) ◽  
pp. 933-938 ◽  
Author(s):  
Marten Fålkenberg ◽  
Johan Tjärnstrom ◽  
Per Örtenwall ◽  
Michael Olausson ◽  
Bo Risberg
Keyword(s):  
Endothelial Cells ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Vasa Vasorum ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Tissue Plasminogen ◽  
The Media ◽  
Activator Inhibitor ◽  
Pai 1

SummaryLocal fibrinolytic changes in atherosclerotic arteries have been suggested to influence plaque growth and promote mural thrombosis on ruptured or ulcerated plaques. Increased levels of plasminogen activator inhibitor (PAI-1) have been found in atherosclerotic arteries. In this study tissue plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA) and PAI-1 were localized in arterial biopsies of healthy and atherosclerotic vessels by immunohistochemis-try. The expression of fibrinolytic regulators was related to the distribution of endothelial cells (EC) and macrophages. Results: t-PA was expressed in vasa vasorum. PAI-1 was positive in endothelial cells, in the media and in the adventitia. Increased expression of t-PA, u-PA and PAI-1 was found in atherosclerotic vessels. t-PA, u-PA, PAI-1 and macrophages were co-localized in plaques. These results support the concept that macrophages can be important in the local regulation of fibrinolysis in atherosclerotic vessels.

Persistence of Fibrinolytic Activity in Fragments of Human Veins Cultured in Vitro

1970 ◽  
Vol 24 (01/02) ◽  
pp. 043-047 ◽  
Author(s):  
M Pandolfi
Keyword(s):  
Blood Vessels ◽  
Plasminogen Activator ◽  
Fibrinolytic Activity ◽  
Vasa Vasorum ◽  
Adult Human ◽  
Slide Technique

SummaryExplants from 5 adult human veins were cultured in a fibrinolytically inactive medium for 3 weeks and assayed for the presence of plasminogen activator by the fibrin slide technique. The explants from 3 veins showed fibrinolytic activity confined to their vasa vasorum for the whole duration of the culture; no decrease of activity was seen. The finding suggests that small blood vessels are able to synthesize plasminogen activator.

Fibrinolytic Activity of the Arterial Wall

1969 ◽  
Vol 21 (01) ◽  
pp. 001-011 ◽  
Author(s):  
K Onoyama ◽  
K Tanaka
Keyword(s):  
Carotid Artery ◽  
Fibrinolytic Activity ◽  
Arterial Wall ◽  
Aortic Wall ◽  
Internal Carotid ◽  
Atheromatous Plaque ◽  
Human Fibrinogen ◽  
The Media ◽  
The Common ◽  
Almost All

SummaryThe tissue fibrinolysis was studied in 550 specimens of 7 kinds of arteries from 80 fresh cadavers, using Astrup’s biochemical method and Todd’s histochemical method with human fibrinogen.In the microscopically normal aortic wall, almost all specimens had the fibrinolytic activity which was the strongest in the adventitia and the weakest in the media.The fibrinolytic activity seemed to be localized in the endothelium.The stronger activity lay in the adventitia of the aorta and the pulmonary artery and all layers of the cerebral artery.The activity of the intima and media of the macroscopically normal areas seemed to be stronger in the internal carotid artery than in the common carotid artery.Mean fibrinolytic activity of the macroscopically normal areas seemed to decrease with age in the intima and the media of the thoracic aorta and seemed to be low in the cases with a high atherosclerotic index.The fibrinolytic activities of all three layers of the fibrous thickened aorta seemed to decrease, and those of the media and the adventitia of the atheromatous plaque to increase.The fibrinolytic activity of the arterial wall might play some role in the progress of atherosclerosis.

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