Armstrong P B
Department of Zoology, University of California, Davis 95616.
Ciba Found Symp. 1988;141:5-21. doi: 10.1002/9780470513736.ch2.
Intercellular invasion is the intrusion of one tissue into space occupied by a second tissue. The alternative situation to invasion, one characteristic of most coherent tissues, is segregation, with identifiable boundaries between contiguous tissues. Tissue segregation can be demonstrated as an active process by the sorting-out of the disorganized cell aggregates that are produced when mixed suspensions of dissociated cells are caused to reaggregate. In this situation, active reorganization of the disorganized aggregate restores a segregated tissue arrangement. Investigation of the sorting of the two principal tissues of the chick embryonic heart (namely, the myocardium and the mesenchyme) suggests an involvement of a fibronectin-rich interstitial matrix elaborated by the cardiac mesenchyme in the process of tissue segregation. During sorting the matrix appears selectively in regions occupied by the mesenchyme. Under conditions of culture non-permissive for matrix deposition, sorting fails to occur. Stimulation of matrix deposition by the addition of serum, transforming growth factor-beta, or isolated matrix itself is accompanied by sorting-out of the two tissues. The mutual invasion of the two tissues that occurs when mesenchymal and myocardial aggregates are fused occurs in regions where the mesenchymal matrix is lost. It is suggested that the presence of the fibronectin matrix in the cardiac mesenchyme promotes tissue segregation and organizational stability and that its loss establishes conditions in which invasion will occur.
细胞间侵入是指一种组织侵入另一种组织所占据的空间。与侵入相反的情况，即大多数连贯组织的一个特征，是分离，相邻组织之间有可识别的边界。通过将解离细胞的混合悬浮液重新聚集时产生的无序细胞聚集体进行分选，可以证明组织分离是一个活跃的过程。在这种情况下，对无序聚集体的主动重组恢复了分离的组织排列。对鸡胚心脏的两个主要组织（即心肌和间充质）的分选研究表明，心脏间充质产生的富含纤连蛋白的细胞外基质参与了组织分离过程。在分选过程中，该基质选择性地出现在间充质占据的区域。在不允许基质沉积的培养条件下，分选不会发生。通过添加血清、转化生长因子-β或分离的基质本身来刺激基质沉积，会伴随着两种组织的分选。当间充质和心肌聚集体融合时发生的两种组织的相互侵入，发生在间充质基质丢失的区域。有人提出，心脏间充质中纤连蛋白基质的存在促进了组织分离和组织稳定性，而其丢失则建立了发生侵入的条件。
