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RF Levine, A Eldor, E HyAm, H Gamliel, Z Fuks and I Vlodavsky
We have examined the morphological and secretory behavior of rat and guinea
pig megakaryocytes exposed for up to 24 hours to extracellular matrix
produced by cultured bovine endothelial cells. By phase-contrast microscopy
of living cells and in more detail by scanning electron microscopy, the
megakaryocytes showed a nonreversible adherence, an extensive formation of
filopodia around the periphery like the rays of the sun, and a tendency
toward flattening. These filopodia were generally linear with attenuated
tips and were larger than, but resembled the filopodia of, rat or guinea
pig platelets exposed to this extracellular matrix. In contrast, isolated
megakaryocytes on glass or on uncoated plastic surfaces did not show these
responses; adherence, in the face of gentle agitation before fixation, was
minimal, with rare filopodia and no flattening. Megakaryocytes that
interacted with the extracellular matrix produced significant amounts of
thromboxane A2, but this did not occur on uncoated surfaces and could not
be attributed to other contaminating cells in the megakaryocyte
suspensions. The appearance in megakaryocytes of these typical platelet
responses indicates that megakaryocytes acquire the functional capabilities
of platelets by the synthesis and assembly of platelet substances and
organelles. Thromboxane production by megakaryocytes stimulated by the
extracellular matrix is a readily quantifiable measure of this capacity.
This article has been cited by other articles:
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| Copyright © 1985 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
