A study of the relationship between the platelet shape and it's function

It is widely accepted that the platelet which is originally discoid is deformed into spiny spheres by ADP, thrombin or collagen (viscous metamorphosis) and forms thrombus by its function-adhesiveness and aggregation. But we have hardly achieved the quantative analysis of the morphological changes and disclosed the relationship between the deformed platelets and their functions.In order to clarify this relationship, we examined the influences of the following procedures on human platelets.1) preservation (non-anticoagulated whole blood, citrated whole blood), 2) stirring (the same blood samples), 3) preservation after stirring (citrated whole blood) and 4) surgical operation with laparotomy on 10 patients with various diseases.After fixing the platelets by 1% glutaraldehyde, the platelets were classified into disc, hemisphere, sphere and the other form, and checked for pseudopod formation under a light microscope. As a platelet function, platelet retention rate was measured by a modified Hellem-II method.Platelet shape was easily changed and pseudopods issued by preservation and stirring. These morphological changes were brought about more strikingly by stirring than by preservation. The retension rate decreased when spherification and pseudopod formation had prominently advanced. However, it increased when the incidences of non-discoids and the pseudopods increased to some degree, e. g. when citrated blood was preserved up to 60min. at room temperature and when it was stirred for 1min. These phenomena were similarly observed in vivo condition (during operation).These results suggested that some relationship existed between the platelet shape and its function and that halfly deformed platelets were in an activated phase and prominently deformed platelets were rather in a refractory phase. This relationship was probably derived fromnot only extra-platelet factors such as activation of plasma coagulation factors (contact factor and prothrombin) but also from internal factors (or character) of platelets. The latter factors were considered to be more important because both shape change and the increase of retention rate were demonstrated in some experiments to occur before the silicon PTT became shortened.