Golding Jon P, Dixon Monica, Gassmann Martin
Division of Neurobiology, National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK.
Development. 2002 Mar;129(5):1095-105. doi: 10.1242/dev.129.5.1095.
Within the developing vertebrate head, neural crest cells (NCCs) migrate from the dorsal surface of the hindbrain into the mesenchyme adjacent to rhombomeres (r)1 plus r2, r4 and r6 in three segregated streams. NCCs do not enter the intervening mesenchyme adjacent to r3 or r5, suggesting that these regions contain a NCC-repulsive activity. We have used surgical manipulations in the chick to demonstrate that r3 neuroepithelium and its overlying surface ectoderm independently help maintain the NCC-free zone within r3 mesenchyme. In the absence of r3, subpopulations of NCCs enter r3 mesenchyme in a dorsolateral stream and an ectopic cranial nerve forms between the trigeminal and facial ganglia. The NCC-repulsive activity dissipates/degrades within 5-10 hours of r3 removal. Initially, r4 NCCs more readily enter the altered mesenchyme than r2 NCCs, irrespective of their maturational stage. Following surface ectoderm removal, mainly r4 NCCs enter r3 mesenchyme within 5 hours, but after 20 hours the proportions of r2 NCCs and r4 NCCs ectopically within r3 mesenchyme appear similar.
在发育中的脊椎动物头部，神经嵴细胞（NCCs）从后脑的背表面迁移到与菱脑节（r）1加r2、r4和r6相邻的间充质中，形成三条分离的迁移流。NCCs不会进入与r3或r5相邻的中间间充质，这表明这些区域存在NCC排斥活性。我们在鸡身上进行了手术操作，以证明r3神经上皮及其上方的表面外胚层独立地有助于维持r3间充质内的无NCC区。在没有r3的情况下，NCCs亚群以背外侧流的形式进入r3间充质，并且在三叉神经节和面神经节之间形成一条异位颅神经。在去除r3后的5-10小时内，NCC排斥活性消散/降解。最初，无论r4 NCCs和r2 NCCs的成熟阶段如何，r4 NCCs比r2 NCCs更容易进入改变后的间充质。去除表面外胚层后，主要是r4 NCCs在5小时内进入r3间充质，但在20小时后，r3间充质内异位的r2 NCCs和r4 NCCs的比例似乎相似。
