MEDIAL EDGE EPITHELIUM TRANSFORMS TO MESENCHYME AFTER EMBRYONIC PALATAL SHELVES FUSE
MEDIAL EDGE EPITHELIUM TRANSFORMS TO MESENCHYME AFTER EMBRYONIC PALATAL SHELVES FUSE
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DOI：
10.1016/s0012-1606(89)80017-x
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发表时间：
1989-02-01
影响因子：
2.7
通讯作者：
HAY, ED
中科院分区：
文献类型：
--
作者：
FITCHETT, JE;HAY, ED
腭中缘上皮细胞（palatal medial edge epithelium，EEP）在第二代腭架融合后消失，常被认为是胚胎细胞程序性死亡导致的重塑的典型例子。我们在16天的大鼠胚胎中重新研究了这种现象，使用光学和电子显微镜。我们证实了关于在货架处于水平位置后，双层货架的周壁开始斯劳脱落的报告。在体外，表皮细胞不能斯劳，而是在粘附过程中被捕获。然而，在体内，表面细胞脱落之前，在前腭的架子坚持，允许连接之间形成相对的基底上皮细胞。这样形成的中线接缝由两层基底细胞组成，所有这些细胞都看起来很健康。即使细胞在分裂，缝的生长也跟不上腭的生长，它会变薄到一层细胞，然后分裂成小岛。基膜消失，伸长的纤毛细胞将丝状伪足延伸到邻近的结缔组织中。电子显微镜显示上皮细胞特征的丧失和转化成纤维细胞样特征的获得的过渡步骤。一个这样的功能，观察与免疫荧光的帮助下，是转间充质细胞骨架蛋白，波形蛋白。在大部分腭部粘附和变薄后，未观察到细胞死亡或巨噬细胞。这些数据表明，间充质细胞是一种外胚层，保留了转化为间充质细胞的能力。上皮-间质转化可能在其他胚胎重塑中表达（R。L. Trelstad，A.林角Hayashi和P.K. Donahue，1982，Dev. 92，27），导致迄今为止未被怀疑的胚胎细胞群的保存。
The disappearance of palatal medial edge epithelium (MEE) after fusion of secondary palatal shelves is often cited as a classical example of embryonic remodeling by programmed cell death. We reinvestigated this phenomenon in 16-day rat embryos, using light and electron microscopy. We confirm reports that the periderm of the two-layered MEE begins to slough after shelves assume horizontal positions. In vitro, peridermal cells are not able to slough and are trapped during the adhension process. In vivo, however, surface cells shed before the shelves in the anterior palate adhere, allowing junctions to form between opposing basal epithelial cells. Midline seams so formed consist of two layers of basal cells, all of which appear healthy. Even though its cells are dividing, growth of the seam fails to keep pace with palatal growth and its thins to one layer of cells, and then breaks up into small islands. The basal lamina disappears and elongating MEE cells extend filopodia into adjacent connective tissue. Electron micrographs reveal transitional steps in loss of epithelial characteristics and gain of fibroblast-like features by transforming MEE cells. One such feature, observed with the aid of immunofluorescence, is the turn of the mesenchymal cytoskeletal protein, vimentin. No cell death or macrophages are observed after adhension and thinning over most of the palate. These data indicate that MEE is an ectoderm that retains the ability to transform into mesenchymal cells. Epithelial-mesenchymal transformation may be expressed in other embryonic remodelings (R. L. Trelstad, A. Hayashi, K. Hayashi, and P. K. Donahue, 1982, Dev. Biol. 92, 27), resulting in heretofore unsuspected conservation of embryonic cell populations.