Muto M
Arch Histol Jpn. 1976 Mar;39(1):51-66. doi: 10.1679/aohc1950.39.51.
Bone marrow sinuses of young rats were examined under the scanning (SEM) and transmission electron microscopes (TEM). Marrow sinus wall was composed of three layers: an inner or luminal endothelium, an outer or adventitial cell layer, and a basal lamina in between. The luminal surface of the endothelial cells was quite smooth and showed some fenestrations, which could be divided into two types according to their size. One was represented by larger fenestrations (1-3 mum in diameter) which were presumed to be formed transiently at the site of blood cell migration, while the other by small pores (0.1 mum) grouped into a cribriform area. The adventitial cells showed a discontinuous layer in the TEM. Under the SEM, the discontinuity corresponded to the spaces formed between the cytoplasmic attenuations of the cells. Blood cell migration from the extravascular hemopoietic tissue into the sinus lumen was numerously observed. The migration occurred not through an intercellular gap, but through the larger intracellular fenestration of the endothelial lining mentioned above. A number of megakaryocytes were identified by their bulky cytoplasm in the parenchyme. Figures suggesting the sequence of platelet liberation from this cell could be demonstrated. First, the megakaryocyte extended its peripheral cytoplasmic processes into the sinus through endothelial fenestrations. The processes, being conspicuously extended, became periodically constricted. Finally, platelets were believed to be produced by separation at the constricted portions and liberated to circulation. The occurrence of a few endothelial fenestrations apparently unassociated with blood cell migration may possibly be ascribed to detachment of a blood cells due to vascular perfusion. The functional significance of the adventitial cell was discussed in association with blood cell migration.
对幼鼠的骨髓窦进行了扫描电子显微镜（SEM）和透射电子显微镜（TEM）检查。骨髓窦壁由三层组成：内层或管腔内皮、外层或外膜细胞层以及其间的基膜。内皮细胞的管腔表面相当光滑，有一些窗孔，根据其大小可分为两种类型。一种以较大的窗孔（直径1 - 3微米）为代表，推测是在血细胞迁移部位短暂形成的，而另一种是由聚集在筛状区域的小孔（0.1微米）组成。在透射电子显微镜下，外膜细胞呈不连续层。在扫描电子显微镜下，这种不连续性对应于细胞胞质变薄之间形成的间隙。大量观察到血细胞从血管外造血组织迁移到窦腔。迁移不是通过细胞间隙，而是通过上述内皮衬里较大的细胞内窗孔。在实质中通过其庞大的细胞质鉴定出许多巨核细胞。可以证明表明血小板从该细胞释放顺序的图像。首先，巨核细胞通过内皮窗孔将其外周细胞质突起延伸到窦中。这些突起明显延伸并周期性收缩。最后，血小板被认为是在收缩部位分离产生并释放到循环中。一些明显与血细胞迁移无关的内皮窗孔的出现可能归因于血管灌注导致的血细胞脱离。结合血细胞迁移讨论了外膜细胞的功能意义。
