Tavassoli M, Aoki M
Br J Haematol. 1981 May;48(1):25-9. doi: 10.1111/j.1365-2141.1981.00025.x.
Electron microscopic evidence is presented to indicate that entire megakaryocytes traverse the marrow--blood barrier and enter the circulation. Passage occurs through apertures of 6 micrometer in diameter, located in the parajunctional areas of the marrow sinus endothelium. Serial sectioning indicates that these apertures are transendothelial rather than interendothelial. The cytoplasm of these megakaryocytes form sinuating elongated projections which may release their platelets in the sinus lumen or when reaching the pulmonary circulation. In the extravascular compartments, megakaryocytes are preferentially located in the subendothelial region. In this location they can send numerous organelle-free projections into the lumen. These projections distinguishable from less numerous organelle-containing projections could serve to 'anchor' the cell to the endothelium. They could also serve to 'monitor' the circulation and to receive information as to the requirement of body for platelet formation.
电子显微镜证据表明，整个巨核细胞穿过骨髓 - 血屏障并进入循环系统。通过位于骨髓窦内皮细胞旁连接区域直径为6微米的小孔进行通道运输。连续切片显示这些小孔是跨内皮的而非内皮间的。这些巨核细胞的细胞质形成蜿蜒的细长突起，这些突起可能在窦腔内或到达肺循环时释放其血小板。在血管外间隙中，巨核细胞优先位于内皮下区域。在这个位置，它们可以向腔内发送大量不含细胞器的突起。这些与较少数量的含有细胞器的突起不同的突起可用于将细胞“锚定”在内皮上。它们还可以用于“监测”循环系统，并接收有关身体对血小板生成需求的信息。
