Radley J M, Hartshorn M A, Green S L
Biological Research Unit, Cancer Institute, Melbourne, Australia.
Thromb Haemost. 1987 Aug 4;58(2):732-6.
The response of megakaryocytes to thrombin (1-10 U/ml) has been examined by time-lapse cinemicrography and electron microscopy. The study was confined to mature megakaryocytes which had developed processes following incubation in vitro. The initial response of all cells was to undergo retraction of processes, behaviour thought to be linked with the depolymerization of microtubules which extend longitudinally through the processes. The majority of cells completely withdrew their processes, but about 30% responded differently and underwent only limited retraction, followed by secretion. Analysis of time-lapse film showed that processes from the latter group of cells had formed attachments with the coverslip prior to exposure to thrombin. Within the partially retracted processes of these cells, secretory granules were found to be clustered centripetally and enveloped by a microfilamentous structure in the form of a cylinder. Vacuoles appeared, some of which were located outside the microfilamentous structure. Microtubules were present, but many appeared disorientated. The shape of the microfilamentous structure suggests that the cytoplasm is not organized into putative platelets at the time of process formation.
通过延时电影显微镜和电子显微镜检查了巨核细胞对凝血酶（1-10 U/ml）的反应。该研究仅限于在体外培养后已形成突起的成熟巨核细胞。所有细胞的初始反应是突起回缩，这种行为被认为与纵向贯穿突起的微管解聚有关。大多数细胞完全缩回其突起，但约30%的细胞反应不同，仅经历有限的回缩，随后分泌。对延时电影的分析表明，后一组细胞的突起在暴露于凝血酶之前已与盖玻片形成附着。在这些细胞部分回缩的突起内，发现分泌颗粒向心聚集，并被呈圆柱体形式的微丝状结构包裹。出现了液泡，其中一些位于微丝状结构之外。微管存在，但许多看起来方向紊乱。微丝状结构的形状表明，在突起形成时，细胞质并未组织成假定的血小板。
