Microtubule coils in spread blood platelets
JG White and JJ Sauk
The fate of the circumferential bundle of microtubules in activated
platelets has been a subject of disagreement. Thin sections of stimulated
platelets fixed at multiple intervals following exposure to aggregating
agents have revealed that the circumferential band is constricted into a
tight ring around centrally concentrated organelles. However, studies of
detergent-resistant platelet cytoskeletons fixed and either negatively
stained or critical point dried after activation on polylysine-coated grids
have revealed that microtubule rings disappear, leaving only fragments in
the peripheral cytoplasm of spread cells. The present study has employed
immunofluorescence on glass slides and the whole mount technique with
detergent extraction and either negative staining or critical point drying
to evaluate the fate of microtubules in surface-activated platelets treated
with or without the microtubule stabilizing agent, taxol. Significant
numbers of microtubule coils were visible in control and taxol-treated
platelets stained indirectly with a fluorescein-coupled antibody to tubulin
30 to 60 minutes after surface activation on glass. Coils of microtubules
were also visible in dendritic forms and in significant numbers of spread
platelets on negatively stained or critical point dried whole mounts in the
electron microscope. The findings support the concept that microtubule
disassembly is not an integral step in early phases of platelet activation.
Volume 64,
Issue 2,
pp. 470-478,
08/01/1984
Copyright © 1984 by The American Society of Hematology
