The development of late gastrula explants of Rana pipiens in salt solution.
The development of late gastrula explants of Rana pipiens in salt solution.
复制标题
淡色林蛙晚期原肠胚外植体在盐溶液中的发育。
DOI：
10.1002/jez.1401000313
复制
发表时间：
1945
期刊：
影响因子：
--
通讯作者：
H. Emerson
中科院分区：
文献类型：
--
作者：
H. Emerson
有三项研究报道了尖音蛙蝌蚪尾部组织再生过程中晚期原肠胚外胚层的发育（Emerson，'42-' 44）。在原肠胚阶段，有三个地形不同的外胚层区域，外胚层的部分已经由脊索中胚层，游离囊胚腔屋顶的小剩余区域，以及腹面唇附近的区域，其由卵黄和内陷的中胚层所覆盖。将这三个外胚层区域移植到尾芽基中，形成定形表皮、吸盘和角质颚;整个外胚层表面的任何部分的器官发育频率大致相同。鼻囊也经常来自外胚层的任何部分，其已经被索中胚层所覆盖，并且它们可以在没有任何神经组织存在的情况下发育。有时，在完全没有视杯的情况下，晶状体来自下层外胚层。吸盘、角质颚和鼻囊等器官的形成，距离它们假定的位置如此之远，这需要解释。众所周知，当在盐溶液中分离时，吸盘来自早期原肠胚外胚层的任何部分（Holtfreter，'38 b）。Holtfreter解释说，这是由于小的外胚层外植体从正常胚胎环境的假设抑制作用中释放出来。在芽基中出现的来自晚期原肠胚分离物的各种外胚层器官，也许也可以用同样的方法来解释。另一方面，越来越多的证据表明，引起胚胎诱导的刺激可能是某种非特异性的，在某些情况下，几个因素可能相互替代，引起相同的诱导（Hamburger，'44）。由于这个原因，芽基中可能存在与正常胚胎刺激相似或相同的因子，从而导致各种外胚层器官从有能力的胚形成。
Three studies have been reported on the development of late gastrula ectoderm in the midst of regenerating tail tissue of Rana pipiens tadpoles (Emerson,'42-'44). In the gastrula stage there are three topographically different ectodermal regions, the part of the ectoderm already underlain by chordamesoderm, the small remaining region of free blastocoel roof, and the area near the ventral lip which is underlain by yolk and invaginated mesoderm. Transplants of all three of these ectodermal regions into the tail blastema form definitive epidermis, suckers, and horny jaws; and the organs develop with about the same frequency from any part of the entire ectodermal surface. Nasal sacs also often come from any part of the ectoderm which is already underlain by chordamesoderm, and they may develop without the presence of any nervous tissue. Occasionally lenses come from underlain ectoderm in the entire absence of an optic cup. The formation of such organs as suckers, horny jaws, and nasal sacs from regions so far from their presumptive locations demands explanation. It is well known that suckers come from any part of the early gastrula ectoderm when it is isolated in salt solution (Holtfreter,'38b). This was explained by Holtfreter as being due to release of the small ectodermal explants from the hypothetical inhibitory action of their normal embryonic environment. The appearance of the various ectodermal organs which come from late gastrula isolates in the blastema can perhaps be explained in the same way. On the other hand, evidence is accumulating that the stimuli causing embryonic inductions may be somewhat non-specific, and that in certain cases several factors may substitute for each other in bringing about the same induction (Hamburger,'44). For this reason there may be factors in the blastema which are similar to or identical with the normal embryonic stimuli causing the formation of various ectodermal organs from competent