Osafune Kenji, Nishinakamura Ryuichi, Komazaki Shinji, Asashima Makoto
Department of Life Sciences (Biology), Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Dev Growth Differ. 2002 Apr;44(2):161-7. doi: 10.1046/j.1440-169x.2002.00631.x.
The earliest form of embryonic kidney, the pronephros, consists of three components: glomus, tubule and duct. Treatment of the undifferentiated animal pole ectoderm of Xenopus laevis with activin A and retinoic acid (RA) induces formation of the pronephric tubule and glomus. In this study, the rate of induction of the pronephric duct, the third component of the pronephros, was investigated in animal caps treated with activin A and RA. Immunohistochemistry using pronephric duct-specific antibody 4A6 revealed that a high proportion of the treated explants contained 4A6-positive tubular structures. Electron microscopy showed that the tubules in the explants were similar to the pronephric ducts of normal larvae, and they also expressed Gremlin and c-ret, molecular markers for pronephric ducts. These results suggest that the treatment of Xenopus ectoderm with activin A and RA induces a high rate of differentiation of pronephric ducts, in addition to the differentiation of the pronephric tubule and glomus, and that this in vitro system can serve as a simple and effective model for analysis of the mechanism of pronephros differentiation.
胚胎肾的最早形式，即前肾，由三个部分组成：肾小球、肾小管和导管。用激活素A和视黄酸（RA）处理非洲爪蟾未分化的动物极外胚层可诱导前肾小管和肾小球的形成。在本研究中，对用激活素A和RA处理的动物帽中前肾导管（前肾的第三个组成部分）的诱导率进行了研究。使用前肾导管特异性抗体4A6进行免疫组织化学分析显示，很大比例的处理过的外植体含有4A6阳性管状结构。电子显微镜检查表明，外植体中的小管与正常幼虫的前肾导管相似，并且它们还表达Gremlin和c-ret，这两种是前肾导管的分子标志物。这些结果表明，用激活素A和RA处理非洲爪蟾外胚层，除了诱导前肾小管和肾小球分化外，还能诱导较高比例的前肾导管分化，并且这种体外系统可作为分析前肾分化机制的简单而有效的模型。
