Mayordomo R, Alvarez I S
Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain.
J Craniofac Genet Dev Biol. 2000 Apr-Jun;20(2):64-75.
The formation of the midbrain region depends mainly on the activity of a signalling center located in the isthmus region, on the border between the prospective mesencephalon and metencephalon. FGF-8 has been proposed as a signalling molecule responsible for this specification because of its expression pattern and its ability to elicit duplication of the midbrain region when expressed ectopically in the neuroepithelium. Here we present evidence that members of the FGF family of growth factors when released in the cephalic mesenchyme are able to extend the expression of the mesencephalic marker En-2 to both the anterior and the posterior regions of its original landmark. This alteration in the expression pattern of En-2 is not accompanied by a significant alteration in the later development of the midbrain-cerebellar anlage, although the eye development is severely altered. Members of the bone morphogenetic protein family ectopically released from the mesenchyme down-regulate the expression of En-2 and also have an effect on the development of the eye. These results demonstrate that growth factor molecules produced in the mesenchyme (vertical signalling) participate in the correct establishment of the antero-posterior patterning of the cephalic nervous system during development.
中脑区域的形成主要取决于位于峡部区域（即预期中脑和后脑之间的边界）的信号中心的活动。由于其表达模式以及在神经上皮中异位表达时引发中脑区域重复的能力，FGF - 8被认为是负责这种特化的信号分子。在此我们提供证据表明，生长因子FGF家族的成员在头部间充质中释放时，能够将中脑标记物En - 2的表达扩展到其原始标记的前部和后部区域。En - 2表达模式的这种改变在中脑 - 小脑原基的后期发育中并未伴随显著改变，尽管眼睛发育受到严重影响。从间充质中异位释放的骨形态发生蛋白家族成员会下调En - 2的表达，并且也对眼睛的发育产生影响。这些结果表明，间充质中产生的生长因子分子（垂直信号传导）在发育过程中参与了头部神经系统前后模式的正确建立。
