The cytoskeleton of blood platelets viewed by immunofluorescence microscopy.

Immunofluorescence microscopy has been used to characterize the morphological transitions that occur as platelets spread on a surface. Antibodies to the microfilament-specific proteins, actin, myosin, tropomyosin, alpha-actinin and filamin as well as antibodies to tubulin were used. Antibody to tubulin reveals the marginal band of microtubules as a bright fluorescent ring, the diameter of which decreases at a time coincident with pseudopod formation. The latter process is dictated by the assembly of microfilament bundles. Although the change in morphology of the platelet was not studied in detail, our data support the idea that microfilament reorganization influences the display of the marginal band of microtubules. A further conclusion is that the platelet in spite of its small diameter is a system suitable for immunofluorescence microscopy, a method which allows the rapid and simultaneous screening of many cells.