Ultrastructural Study on the Release Reaction of the Platelet

Kawaguchi, Yukihiro

doi:10.1111/j.1440-1827.1982.tb02079.x

Cited by 8 publications

(1 citation statement)

References 32 publications

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“…Platelet shape change is characterized by the breakdown and reorganization of cytoskeletal components (microtubules and microfilaments) which lead to the release of platelet granules [15][16][17]33]. thrombin).…”

Section: In Vitro Studiesmentioning

confidence: 99%

Tumor cell-platelet interactions in vitro and their relationship to in vivo arrest of hematogenously circulating tumor cells

et al. 1987

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Aggregation of rat platelets was induced in vitro by homologous rat Walker 256 carcinosarcoma cells and the extent of tumor cell-platelet interactions examined ultrastructurally. By 30s there was surface contact between unstimulated platelets and tumor cell microvilli. By midphase aggregation (2-3 min) tumor cells became enmeshed within expanding platelet aggregates. Tumor cell microvilli and platelet pseudopodia interdigitated as aggregation progressed. During the later stages of aggregation (6-10 min) tumor cells formed large processes which penetrated deep into the aggregate. Platelet activation (i.e. degranulation) occurred in gradient fashion and was concentrated near tumor cell membrane sites involved in process formation. At these later stages tumor cells near the aggregate periphery were found to have engulfed platelets or platelet fragments. Tumor cell-platelet interactions in the pulmonary microvasculature were also studied in vivo following injection of murine Lewis lung carcinoma, 16C mammary adenocarcinoma, and B16 amelanotic melanoma tumor cells into the tail vein. Platelets demonstrated a biphasic association with arrested tumor cells with peak interactions occurring at 10-30 min and 4-24 h. Ultrastructurally, tumor cells exhibited newly formed processes which interdigitated with the platelet aggregate. Such processes formed only in areas of contact with platelets and not in areas of contact with endothelial cells or other blood elements (i.e. erythrocytes, polymorphonuclear leukocytes). Numerous tumor cell mitochondria were concentrated in the areas of greatest platelet-tumor cell process activity. At early time intervals (2-10 min), intravascular platelet degranulation was observed primarily in platelets associated with tumor cell processes. Tumor cells also were found to have engulfed platelet fragments in vivo.

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Section: In Vitro Studiesmentioning

confidence: 99%

Tumor cell-platelet interactions in vitro and their relationship to in vivo arrest of hematogenously circulating tumor cells

et al. 1987

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Platelet secretion during clot retraction

White

2000

Platelets

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The precise route serving as the pathway for extrusion of products contained in platelet storage organelles following cell activation has been controversial for many years. Some workers believe that the granules and dense bodies fuse together to form secretion vacuoles that move to the exposed cell surface, fuse with it and extrude contained products to the outside. Others suggest that the organelles fuse with channels of the open canalicular system (OCS) and deposit their contents which are subsequently secreted to the exterior. The controversy has been difficult to resolve because nearly all workers have used platelets in suspension to arrive at diverse conclusions. The present study has used ethylenediamine tetracetic acid (EDTA)-treated platelets and isometric clot retraction as a model system, and either polylysine or tannic acid to define the pathway used for secretion. Results indicate that secretion takes place in EDTA platelets under isometric tension by fusion of granules to OCS channels and passage of products through these conduits to the cell exterior. There is no evidence to suggest the organelles form secretion vacuoles or extrude their products by fusion with the inside of the exposed surface membrane.

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The Distribution of Concanavalin A‐ And Cationized Ferritin‐Binding Sites on Plasma Membrane of Human Platelet and the Changes of These Sites in Cells Responding to Adenosine Diphosphate

Yotsumoto

1984

Acta Pathologica Japonica

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Investigations were carried out to study the distribution of the concanavalin A‐ and cationized ferritin‐binding sites on the plasma membrane of human platelets and to ascertain the changes of these sites in cells stimulated with adenosine diphosphate (ADP) with time as well. The concanavalin A‐binding sites of the unwashed fixed platelets were sparsely distributed on the plasma membrane at a distance of up to 80 nm from the outer leaflet of the plasma membrane. The washed unfixed platelets, however, showed a dense distribution within a range of 70 nm from the outer leaflet of the plasma membrane. Changes in the distribution of concanavalin A‐binding sites on the plasma membrane of platelets stimulated with ADP were characterized by a marked increase in the number of binding sites and by protrusion up to a distance of 150 nm from the outer leaflet of the plasma membrane 1 minute after the reaction had occurred. The concanavalin‐A binding sites may be semicryptic in view of the fact that they were exposed by washing or protruded as a result of the stimulation with ADP. The cationized ferritin binding sites were uniformly distributed with high density on the plasma membrane of the unwashed fixed platelets. In washed unfixed platelets, however, they were sparsely distributed with cluster formation. It is suggested that the glutaraldehyde fixation itself has an effect on the binding of the cationized ferritin particles on the plasma membrane of plateletes. The various changes in the concanavalin A‐binding sites appearing 1 minute after the reaction with ADP may represent morphological evidence indicating that the platelets have acquired adhesiveness.

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Ultrastructural Study on the Release Reaction of the Platelet

Cited by 8 publications

References 32 publications

Tumor cell-platelet interactions in vitro and their relationship to in vivo arrest of hematogenously circulating tumor cells

Tumor cell-platelet interactions in vitro and their relationship to in vivo arrest of hematogenously circulating tumor cells

Platelet secretion during clot retraction

The Distribution of Concanavalin A‐ And Cationized Ferritin‐Binding Sites on Plasma Membrane of Human Platelet and the Changes of These Sites in Cells Responding to Adenosine Diphosphate

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