STRUCTURAL DEVELOPMENT OF ENDOCARDIAL CUSHIONS
STRUCTURAL DEVELOPMENT OF ENDOCARDIAL CUSHIONS
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DOI：
10.1002/aja.1001480108
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发表时间：
1977-01-01
影响因子：
--
通讯作者：
MANASEK, FJ
中科院分区：
文献类型：
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作者：
MARKWALD, RR;FITZHARRIS, TP;MANASEK, FJ
对鸡[胚胎]和大鼠[胚胎]心内膜垫（心脏间质）的发育进行了组织学（使用Nomarski差示干涉光学观察活组织和非固定组织）、超微结构（扫描和透射）、细胞化学（使用酸化透析铁作为聚负离子材料的视觉探针）和放射自显影（使用35S）研究，以阐明间质的起源。通过迁移间充质细胞导致缓冲层形成和硫代糖胺聚糖分泌的形态学序列。两个物种的垫层形成相似。间充质细胞最初出现在16- 18体胚胎中，位于未来房室管和流出道的内皮（缺乏基板）下方。缓冲间充质细胞的细胞质结构与内皮细胞相似；这些细胞可能是由内皮细胞的增殖产生的。种子细胞中有丝分裂象也很多。缓冲细胞最初通过桥粒附着在内皮上，但后来获得了运动器官（含有微管和微丝状束的伪足和丝状足）。连续衰老胚胎（20 ~ 44个体）的连续切片显示离心迁移方向。细胞过程与细胞外基质的相互作用表明后者被用作迁移基质。向前推进的楔状缓冲细胞与心肌的接触对有丝分裂活性的细胞结构没有影响。透明质酸酶敏感的透析铁（DI）沉淀在250 nm高尔基液泡中，透明质酸酶敏感的35s产生的银颗粒在缓冲细胞上的定位表明，该组织为基质提供了硫酸大分子。透明质酸酶不稳定的DI物质在包被的内吞样囊泡和小泡中的定位也表明，间充质细胞的迁移可能对基质进行修饰或调节。在发育中的坐垫中建立了发育序列中断可能导致瓣膜或间隔缺陷的位点。
Development of chick [embryo] and rat [embryo] endocardial cushions (cardiac mesenchyme) was studied histologically (using Nomarski differential interference optics on living and unfixed tissue), ultrastructurally (scanning and transmission), electron microscopy cytochemically (using acidified dialyzed Fe as a visual probe for polyanionic material) and autoradiographically (using 35S) to elucidate the origin of the mesenchyme, the morphologic sequences leading to cushion formation and secretion of sulfated glycosaminoglycans, if any, by migrating mesenchymal cells. Cushion formation was similar for both species. Mesenchymal cells appeared initially, in 16- to 18-somite embryos, beneath the endothelium (which lacked a basal lamina) of the future atrioventricular canal and outflow tract. The cytoplasm of cushion mesenchymal cells was structurally similar to the endothelium; probably these cells arose by proliferation of the endothelium. Mitotic figures among the seeded cells were also numerous. Cushion cells were initially attached to the endothelium by desmosomes but acquired motile apparatus (pseudopodia and filopodia containing microtubules and microfilamentous bundles). Serial sectioning of successively-aged embryos (20-44 somites) indicated a centrifugal migratory direction. Interaction of the cell processes with extracellular matrix suggested that the latter was used as a migratory substrate. Contact of the advancing wedge of cushion cells with the myocardium produced no alteration in cell structure of mitotic activity. Localization of hyaluronidase-sensitive, dialyzed iron (DI) precipitates in 250 nm Golgi vacuoles and hyaluronidase-sensitive 35S-engendered silver grains over cushion cells indicated that this tissue contributed sulfated macromolecules to the matrix. Localization of hyaluronidase-labile, DI material in coated, endocytic-like vesicles and caveolae also suggested potential modification or conditioning of the matrix by migrating mesenchymal cells. Loci in developing cushions were established where disruption of the developmental sequence could engender valvular or septal defects.