English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The release reaction of platelets has been assumed to subserve a positive feedback mechanism responsible for their aggregation in haemostasis and thrombosis. This assumption is based mainly on in vitro experiments. Considerable uncertainty remains about the contribution of the release reaction to the initiation of haemostasis in vivo. The rapidity of the process and the presence of other tissues makes it impossible to follow the reaction quantitatively in vivo by methods which permit this in vitro. We have therefore applied quantitative electron microscopy to find out how quickly the concentration of dense bodies decreases in platelets during their haemostatic aggregation. In mice, platelets were enriched in dense bodies by pretreatment with serotonin.  Mesenteric arteries were incised with a sharp blade. Bleeding was stopped by a micromanipulator-operated device about 15 sec and 60 sec after the cut. The cut segments were immediately fixed in situ with glutaraldehyde and postfixed. Serial sections were made for electron microscopy. Platelets isolated from peripheral blood of the same animal were prepared similarly. Electron micrographs were projected on to a television screen and numbers of dense bodies and total platelet areas were determined by an image analysing computer. After 15 sec there were no significant differences in numbers of dense bodies in platelets from different parts of the haemostatic plugs (8.31±0.57/100 μ2 mean ± s.e.m.) and in platelets from the blood (8.93±0.38). On the other hand, after 60 sec the parts furthest from the cut contained fewer dense bodies than the nearer parts and the overall dense body number (5.86±0.05) was considerably smaller (p&lt;0.001) than that of platelets from the blood (14.45±0.09).  The results suggest that haemostatic aggregation of platelets does not initially depend on their release reaction.

The Time Relation Between The Haemostatic Aggregation Of Platelets And Their Release Reaction In Vivo