UNCOUPLING HISTOGENESIS FROM MORPHOGENESIS IN THE VERTEBRATE EMBRYO BY COLLAPSE OF THE TRANSNEURAL TUBE POTENTIAL
UNCOUPLING HISTOGENESIS FROM MORPHOGENESIS IN THE VERTEBRATE EMBRYO BY COLLAPSE OF THE TRANSNEURAL TUBE POTENTIAL
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DOI：
10.1002/aja.1002030408
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发表时间：
1995-08-01
影响因子：
2.5
通讯作者：
SHI, RY
中科院分区：
文献类型：
--
作者：
BORGENS, RB;SHI, RY
我们已经表明，在两栖动物胚胎神经管的腔液的Na+的单向泵产生一个大的电位差（40-90 mV，管腔负的近腔表面）。这种跨神经管电位（TNTP）类似于跨表面外胚层存在的Na+依赖性跨上皮电位（TEP）。当神经褶融合形成神经管时，这种TEP被内化后保留在外胚层中。通过微电极离子导入法将Na+通道阻断剂阿米洛利或苯扎米尔注入管腔内，可显著降低TNTP数小时。在这里，我们描述了TNTP修饰对发育解剖学的影响。用阿米洛利或苯扎明注射具有融合和闭合的神经管的蝾螈胚胎（21-23期），并使其继续发育36-52小时。将这些胚胎与单独注射载体的对照胚胎或阿米洛利或苯扎明仅在表面外胚层下方离子电渗的胚胎进行比较。所有TNTP降低的胚胎都是严重缺陷的。这些的特征是组成已经开始形成的结构（耳原基、脑、脊髓、脊索）的细胞解体以及新结构发育失败。值得注意的是，其中一些胚胎在完全没有伴随的内部组织发生的情况下表现出外部形态的持续发育。我们讨论的方式，其中一个大的内源性电压梯度与上皮电位差（TNTP）可能需要的早期神经上皮的结构完整性，和正常形态发生的先决条件。(C)1995 Wiley-Liss，Inc.
We have shown that unidirectional pumping of Na+ out of the neural tube's luminal fluids in amphibian embryos produces a large potential difference (40-90 mV, lumen negative to the abluminal surface). This transneural tube potential (TNTP) is analogous to the Na+ dependent transepithelial potential (TEP) that exists across surface ectoderm. This TEP is retained in ectoderm after it is internalized when the neural folds fuse to form the neural tube. The TNTP can be markedly reduced for several hours by injection of the Na+ channel blockers amiloride or benzamil into the lumen by iontophoresis through microelectrodes. Here we describe the effect of TNTP modification on developmental anatomy. Axolotl embryos possessing a fused and closed neural tube (stage 21-23) were injected with either amiloride or benzamil and allowed to continue development for 36-52 hr. These were compared to control embryos injected with vehicle alone, or to embryos in which amiloride or benzamil was iontophoresed just beneath surface ectoderm. All embryos in which the TNTP was reduced were grossly defective. These were characterized by a disaggregation of the cells comprising the structures that had already begun to form (otic primordia, brain, spinal cord, notochord) as well as a failure in the development of new structures. Remarkably, some of these embryos displayed continuing development of external form in the complete absence of concomitant internal histogenesis. We discuss the ways in which a large endogenous voltage gradient associated with an epithelial potential difference (the TNTP) may be required both for the structural integrity of the early neuroepithelium, and a prerequisite for normal morphogenesis. (C) 1995 Wiley-Liss, Inc.