Wassef M, Bally-Cuif L, Alvarado-Mallart R M
INSERM U106, Hôpital de la Salpêtrière, Paris, France.
Perspect Dev Neurobiol. 1993;1(3):127-32.
At early phases of development (stage HH12 of chick and quail embryos) the rostral part of the cerebellar anlage extends into the caudal third of the mesencephalic vesicle. This region is characterized by its high level of expression of the Wnt-1 and engrailed genes, which encode, respectively, for a secreted molecule and for a homeodomain protein. In order to analyze the potentialities of various parts of the cerebellar anlage, pieces of quail or mouse embryonic neural tubes have been transplanted heterotopically in the prosencephalon of HH12 chick embryos. These experiments indicated that signals operating in the plane of the neural tube are still operating in the donor avian and murine embryos. The met- mes- and prosencephalic territories of HH12 chick embryos are still competent to change their fates under the influence of these signals. It was also found that the Wnt-1 expression domain, the caudal mesencephalic vesicle, has striking organizing properties until late stages of development in avian and rodent embryos. The exact role of Wnt-1 in these inductive interactions is still unknown. Wnt-1 influence on cell fate could be mediated by the engrailed genes. Observations suggesting a later role of en-2 in the regionalization of the cerebellar cortex are also reported.
在发育早期阶段（鸡和鹌鹑胚胎的HH12期），小脑原基的头端部分延伸至中脑泡的尾端三分之一处。该区域的特征在于其Wnt-1和engrailed基因的高表达水平，这两个基因分别编码一种分泌分子和一种同源域蛋白。为了分析小脑原基各部分的潜能，已将鹌鹑或小鼠胚胎神经管片段异位移植到HH12期鸡胚胎的前脑。这些实验表明，在神经管平面起作用的信号仍在供体鸟类和小鼠胚胎中起作用。HH12期鸡胚胎的中脑、间脑和前脑区域在这些信号的影响下仍有能力改变其命运。还发现，Wnt-1表达域，即尾端中脑泡，在鸟类和啮齿动物胚胎发育的后期阶段具有显著的组织特性。Wnt-1在这些诱导相互作用中的确切作用仍不清楚。Wnt-1对细胞命运的影响可能由engrailed基因介导。还报道了一些观察结果，提示en-2在小脑皮质区域化中起后期作用。
