Harrisson F, Van Nassauw L, Van Hoof J, Foidart J M
Department of Human Anatomy and Embryology, University Centre of Antwerp, Antwerpen, Belgium.
Anat Rec. 1993 Aug;236(4):685-96. doi: 10.1002/ar.1092360413.
The involvement of fibronectin in adhesion and migration of individual mesoblast cells during chicken gastrulation was examined after microinjection of functional and nonfunctional antifibronectin antibodies in the blastoderm during the period of rapid migration of mesoblast cells. The injection of affinity-purified polyclonal antihuman fibronectin antibody (total IgG or Fab fragment) or of monoclonal antichicken cellular fibronectin caused a thickening of the primitive streak, which was composed of loosely connected cells. This effect was most evident at the level of Hensen's node, and very few mesoblast cells were observed migrating in the space between upper layer and deep layer. The obvious explanation of this effect was that the de-epithelialization of upper layer cells persisted in the presence of antibodies, but ingressed cells failed to emigrate from the primitive streak. Immunostaining of microinjected antibodies showed binding to the basement membrane, to the cell surface of mesoblast cells that had migrated before microinjection occurred, and to the cell surface of deep layer cells. Cells that ingressed and detached in the course of reincubation of the embryo possessed little immunolabelling along their cell surface. The results suggest that the failure of ingressed cells to emigrate from the primitive streak and to form mesoblast was due (1) to alterations in adhesion between newly ingressed primitive streak cells, which had the ability to detach but possessed relatively little fibronectin along their cell surfaces and a small number of cell protrusions, and (2) probably to a lack of adhesion of detached cells to the basement membrane, which was blocked by the presence of antifibronectin antibodies. We conclude that the presence of fibronectin in the basement membrane is required for emigration of ingressed cells and migration of mesoblast cells to occur. Once migration has commenced, fibronectin is also deposited along the cell surface of migrating cells, a factor that may increase their mutual adhesion.
在中胚层细胞快速迁移期间，向鸡胚盘内显微注射功能性和非功能性抗纤连蛋白抗体后，研究了纤连蛋白在鸡原肠胚形成过程中对单个中胚层细胞黏附与迁移的影响。注射亲和纯化的多克隆抗人纤连蛋白抗体（总IgG或Fab片段）或单克隆抗鸡细胞纤连蛋白会导致原条增厚，原条由连接松散的细胞组成。这种效应在亨氏结水平最为明显，在上层和深层之间的空间中观察到很少有中胚层细胞迁移。对此效应的明显解释是，在上层细胞存在抗体的情况下，上皮细胞脱失持续存在，但侵入细胞未能从原条迁出。显微注射抗体的免疫染色显示，抗体与基底膜、注射前已迁移的中胚层细胞的细胞表面以及深层细胞的细胞表面结合。在胚胎再孵育过程中侵入并脱离的细胞，其细胞表面几乎没有免疫标记。结果表明，侵入细胞未能从原条迁出并形成中胚层的原因是：（1）新侵入的原条细胞之间的黏附发生改变，这些细胞能够脱离，但细胞表面纤连蛋白相对较少且细胞突起数量较少；（2）可能是脱离细胞与基底膜缺乏黏附，抗纤连蛋白抗体的存在阻断了这种黏附。我们得出结论，基底膜中纤连蛋白的存在是侵入细胞迁出和中胚层细胞迁移发生所必需的。一旦迁移开始，纤连蛋白也会沉积在迁移细胞的细胞表面，这一因素可能会增加它们之间的相互黏附。
