Downs K M, Gardner R L
Imperial Cancer Research Fund, Department of Zoology, University of Oxford, UK.
Development. 1995 Feb;121(2):407-16. doi: 10.1242/dev.121.2.407.
Culture of postimplantation conceptuses was used in conjunction with microsurgery to investigate the timing, the mechanism and the developmental regulation of chorioallantoic fusion in the mouse. The timing of fusion was determined in both freshly recovered conceptuses and in those that had been cultured from as early as the mid-streak stage. Attachment of the allantois to the chorion was found to have occurred in most conceptuses by the 6-somite stage, irrespective of whether they had been cultured. In investigating the mechanism of fusion, we wished to determine whether it depended on directed growth of the allantoic bud or on its differential adhesion to the chorion. Microsurgery was used to transplant allantoic tissue into the exocoelomic cavity of conceptuses from which the resident allantois had been removed. In synchronous grafting experiments, transplanted allantoises typically attached to the chorion despite loss of their connection with the hindgut region of the fetus. Hence selective attachment of the allantois to the chorion clearly cannot depend simply on its directed growth. While the transplanted allantoic tissue attached to the chorion selectively, it did not attach to it precociously, despite being favourably positioned to do so. These findings argue that the initial attachment of the allantois to the chorion depends on a selective adhesive mechanism that is developmentally regulated. Further grafting experiments in which donor conceptuses were either more or less advanced than hosts revealed that attachment of the allantois to the chorion depends primarily on the stage of the allantois rather than on the stage of the chorion. Collectively, these findings support the hypothesis that the initial stage of chorioallantoic fusion depends on selective adhesion between regionally differentiated mesodermal surfaces which is governed principally by the stage of development of the allantois.
将植入后胚胎的培养与显微手术相结合，以研究小鼠绒毛膜尿囊融合的时间、机制和发育调控。在刚回收的胚胎以及早在中条纹期就开始培养的胚胎中确定融合的时间。发现大多数胚胎在6体节期时尿囊已附着于绒毛膜，无论它们是否经过培养。在研究融合机制时，我们希望确定它是取决于尿囊芽的定向生长还是其与绒毛膜的差异黏附。使用显微手术将尿囊组织移植到已去除自身尿囊的胚胎的胚外体腔中。在同步移植实验中，尽管移植的尿囊与胎儿后肠区域失去了连接，但它们通常仍附着于绒毛膜。因此，尿囊对绒毛膜的选择性附着显然不能仅仅取决于其定向生长。虽然移植的尿囊组织选择性地附着于绒毛膜，但尽管位置有利，它并没有过早附着。这些发现表明，尿囊对绒毛膜的初始附着取决于一种受发育调控的选择性黏附机制。进一步的移植实验表明，供体胚胎比宿主胚胎发育程度高或低时，尿囊对绒毛膜的附着主要取决于尿囊的阶段而非绒毛膜的阶段。总的来说，这些发现支持了这样一种假设，即绒毛膜尿囊融合的初始阶段取决于区域分化的中胚层表面之间的选择性黏附，这主要由尿囊的发育阶段决定。
