Callebaut M, Van Nueten E
Laboratory of Human Anatomy and Embryology, RUCA, Antwerpen, Belgium.
Eur J Morphol. 1995 Jul;33(3):221-35.
Unincubated quail and prestreak chicken blastoderms were sectioned into cranial, caudal and lateral quadrants and cultured in vitro. Whilst in the caudal and lateral quadrants (containing both endophyll and Rauber's sickle material) a primitive streak (PS) developed, in the cranial quadrants (where merely central endophyll is present) only an ectoblastic thickening (early gastrula: phase I of gastrulation) appeared. If, however, sickle material was grafted on a cranial quadrant then a PS developed (phase II of gastrulation). In the anti-sickle region (lacking sickle material and endophyll) no gastrular differentiation occurred spontaneously. The grafting of endophyll and/or Rauber's sickle evokes here also phase I or II of gastrulation. When the endophyll was removed from the caudal quadrant no PS appeared. If, however, endophyll was replaced, a PS and neurula developed. Our study demonstrates that the presence of endophyll is necessary to obtain an early gastrular development (phase I of gastrulation). It seems also to have an influence on the formation of the future neurectodermal region by induction of a thickening of the cranial upper layer. Only when both endophyll and sickle material were present, a PS formed in caudal quadrants. In the caudal quadrant, the endophyll (which seems to represent the vegetative pole of the avian blastula) does not regenerate, neither from the upper layer, nor from Rauber's sickle (containing blastoporal material: Callebaut and Van Nueten: 1994).
将未孵化的鹌鹑和原条期前的鸡胚盘切成头、尾和侧象限，并进行体外培养。在尾侧和侧象限（同时含有内胚层和劳伯氏新月体物质）中会形成原条，而在头侧象限（仅存在中央内胚层）中仅出现外胚层增厚（早期原肠胚：原肠形成的第一阶段）。然而，如果将新月体物质移植到头侧象限，则会形成原条（原肠形成的第二阶段）。在抗新月体区域（缺乏新月体物质和内胚层），不会自发发生原肠胚分化。移植内胚层和/或劳伯氏新月体也会在此引发原肠形成的第一阶段或第二阶段。当从尾侧象限移除内胚层时，不会出现原条。然而，如果替换内胚层，则会形成原条和神经胚。我们的研究表明，内胚层的存在对于获得早期原肠胚发育（原肠形成的第一阶段）是必要的。它似乎还通过诱导头侧上层增厚对未来神经外胚层区域的形成产生影响。只有当内胚层和新月体物质都存在时，尾侧象限才会形成原条。在尾侧象限，内胚层（似乎代表鸟类囊胚的营养极）不会从上层或劳伯氏新月体（含有胚孔物质：卡勒博特和范努滕，1994）再生。
