Isokawa K, Yi J, Sejima H, Tanaka M, Murakami K, Yokoyama H, Endo S, Komiyama T, Toda Y
Division of Electron Microscopy, Nihon University School of Dentistry, Tokyo, Japan.
J Oral Sci. 1998 Mar;40(1):17-23. doi: 10.2334/josnusd.40.17.
Endothelial cells in the atrioventricular (AV) segment of the developing chicken heart undergo a transition into mesenchymal cells. When the AV segment is explanted onto a hydrated collagen gel, endothelial cells grow out and reproduce in vivo cell transition regardless of the precise orientation of the explant on a gel. Our results showed that when the luminal side of an explant was placed towards a gel surface, the inverted polarity of endothelium was not adjusted by direct reorganization of polarity, but that the endothelium crawled down so as to settle on a gel surface in the correct original cell polarity. Subsequently, endothelial cells showed cytoplasmic hypertrophy, formed microvillous projections and then extended filopodial migratory appendages. These cellular changes were quite similar to those in vivo. However, the continuity of the endothelial layer was specifically disrupted in AV explant cultures. Such disruption was never observed in ventricle explant cultures in which endothelial-mesenchymal cell transition did not occur. The disintegration of AV endothelial outgrowth must be closely related to its capability to transform into mesenchymal cells and mitotic activity to keep a depository of endothelial cells.
发育中的鸡心脏房室（AV）段的内皮细胞会转变为间充质细胞。当将AV段外植到水合胶原凝胶上时，内皮细胞会生长并在体内发生细胞转变，而与外植体在凝胶上的精确方向无关。我们的结果表明，当外植体的腔面朝向凝胶表面放置时，内皮的反转极性并非通过极性的直接重组来调节，而是内皮细胞向下爬行，以便以正确的原始细胞极性在凝胶表面定居。随后，内皮细胞出现细胞质肥大，形成微绒毛突起，然后伸出丝状伪足迁移附属物。这些细胞变化与体内情况非常相似。然而，AV外植体培养中内皮细胞层的连续性被特异性破坏。在未发生内皮-间充质细胞转变的心室外植体培养中从未观察到这种破坏。AV内皮生长物的解体必定与其转化为间充质细胞的能力以及维持内皮细胞储存库的有丝分裂活性密切相关。
