Electron Microscopic Observations on Platelets from Human Blood

Abstract

A suitable and simple technic is described by means of which platelets may be prepared for viewing in the electron microscope. The changes in the shape of platelets spreading on a Formvar film, judged according to predominant forms at successive intervals of time, may be diagramatically expressed as follows Variations of Transitional ("Lysed") "Earliest"[forward arrow]Dendritic] [forward arrow]Neuronal[forward arrow]Transitional[forward arrow]Extended and "Butterfly" [image] This may be contrasted with previous interpretations by others: "Earliest"[forward arrow] Dendritic [forward arrow]Transitional [forward arrow]Extended [forward arrow]"Lysed" Heparin seems to retard the process of spreading. Under the conditions of these experiments, thrombin (Parke, Davis and Company) and thrombokinase (prepared by Dr. J. H. Milstone) are not responsible for producing the forms of platelets heretofore described as "lysed" or "distintegrated." Such a configuration is better explained as a variation of the transitional form of platelets. Additional observations include findings that are suggestive of a double, external hyaloplasmic membrane, and a double membrane about the granules of the granulomere; these may be true structures or fairly symmetric artifacts. Bands of fibrin have a beading of their cross-striations that is suggestive of cross-striations within cross-striations. It is suggested that platelets function as an intact entity in the coagulation of blood and syneresis, and that decomposition of the platelets is not essential; agglutination of the platelets is not necessarily a related phenomenon.