Müller-Glauser W, Haemmerli G, Sträuli P
Cell Biol Int Rep. 1985 May;9(5):447-61. doi: 10.1016/0309-1651(85)90153-5.
The nature of interactions between cells migrating through tissues and their structural surroundings are largely unknown. We have therefore examined the ultrastructural relationship between L5222 rat leukemia cells, moving through the loose connective tissue of the mesentery, and components of the extracellular matrix (ECM). Ultrathin tissue sections, fixed in the presence of ruthenium hexammine trichloride (RHT), revealed the following: Constitutents of fibrillar and nonfibrillar elements of the ECM are in contact with the plasma membrane of L5222 cells. Linear nonfibrillar ECM elements contact the plasma membrane at point-like sites, often associated with root-like structures present within the submembraneous microfilament mesh. Aggregates of ECM material are connected to patch-like cell membrane sites, associated with a condensed, plate-like part of the microfilament mesh. Point-like and patch-like contacts are more numerous at the anterior part of polarized migrating L5222 cells than on the posterior end. In round resting leukemia cells they are evenly distributed around the cell periphery. We suggest that the ECM-cell membrane contacts represent tissue adhesion sites. We therefore hypothesize that in migrating cells a coordinate interaction occurs between the contact sites and the continuous microfilament meshwork which results in a simultaneous backward movement of ECM-membrane contacts on the cell body and in a net forward movement of the whole cell. Since Dembo et al. (1981) present a similar mechanism for in vitro locomotion of granulocytes, we assume that blood cell locomotion in vivo and in vitro depends on similar molecular mechanisms: force generation by the cell, transmembraneous linkage between cytoskeletal and ECM elements, and membrane fluidity. The major difference in blood cell locomotion through a three-dimensional tissue or on a plane substratum would then be given by the distribution of contact sites, occurring around the cell periphery or limited to the ventral cell surface, respectively.
细胞在组织中迁移时与周围结构环境之间相互作用的本质在很大程度上尚不清楚。因此，我们研究了L5222大鼠白血病细胞在肠系膜疏松结缔组织中迁移时与细胞外基质（ECM）成分之间的超微结构关系。用三氯化六氨合钌（RHT）固定的超薄组织切片显示了以下情况：ECM的纤维状和非纤维状成分与L5222细胞的质膜接触。线性非纤维状ECM成分在点状部位与质膜接触，这些部位通常与膜下微丝网络中存在的根状结构相关。ECM物质聚集体与片状细胞膜部位相连，这些部位与微丝网络的浓缩板状部分相关。在极化迁移的L5222细胞前端，点状和片状接触比后端更多。在圆形静止的白血病细胞中，它们在细胞周边均匀分布。我们认为ECM-细胞膜接触代表组织粘附部位。因此，我们假设在迁移细胞中，接触部位与连续的微丝网络之间发生协调相互作用，这导致ECM-膜接触在细胞体上同时向后移动以及整个细胞的净向前移动。由于Dembo等人（1981年）提出了类似的粒细胞体外运动机制，我们假设血细胞在体内和体外的运动取决于类似的分子机制：细胞产生力、细胞骨架与ECM成分之间的跨膜连接以及膜流动性。那么血细胞在三维组织中或在平面基质上运动的主要差异将分别由接触部位的分布给出，接触部位分别出现在细胞周边或仅限于细胞腹侧表面。
