Myogenic specification of somites is mediated by diffusible factors.
Myogenic specification of somites is mediated by diffusible factors.
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体节的肌源性规范是由扩散因子介导的。
DOI：
10.1006/dbio.1995.1130
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Stockdale,FE
中科院分区：
文献类型：
--
作者：
Buffinger,N;Stockdale,FE
用跨滤外植体培养法研究了早期鸡体节和节段板的肌肉发生规范，以确定轴向结构的肌肉发生规范是否由细胞-细胞接触所介导。在神经管和脊索的体节转滤器中评估了表达肌球蛋白重链的肌肉纤维的形成。来自早期鸡胚(ED2)的神经管或脊索诱导未指定体节(汉堡期和汉密尔顿期11-14)的肌肉发生，这些组织被0.2或0.05μ的孔过滤器分开。腹侧神经管是肌肉发生的强烈诱导者，而背侧神经管的诱导活性较低。背神经管成肌诱导活性的降低与抑制特定体节中的成肌分化有关，体节包含已致力于肌肉生成的细胞。在没有神经管的情况下，只需要6-8小时的跨滤器暴露在神经管中就可以启动体节肌发生。来自同一年龄胚胎的其他组织，如特定的体节、心脏或外胚层，不能诱导未特定体节的肌肉发生。在HH阶段8或9移除尾侧神经板的预期底板并不能消除神经外胚层对未指定体节的诱导活性(HH阶段11-14)。逐渐老化胚胎(ED4-20)的体节与神经管或脊髓的重组在各个年龄段都表现出诱导肌化的活性，但随着发育的进行，这种活性逐渐减弱。旁轴中胚层不需要分割成体节来对神经管的诱导活动作出反应。我们得出的结论是，在体节中诱导肌肉发生不需要神经管和脊索之间的细胞-细胞接触，因此诱导是由扩散因子介导的(S)；诱导活性主要定位于脊索和神经管的腹侧半部分，但不一定局限于底板；生肌反应特异于神经管和脊索；背神经管微弱地诱导肌肉发生，并含有抑制肌原细胞分化的活性。
Specification of myogenesis in early chicken somites and segmental plate was studied using transfilter explant cultures to determine if myogenic specification by axial structures is mediated by cell-cell contact. Formation of muscle fibers that express myosin heavy chain was assessed in somites transfilter from neural tube and notochord. Either the neural tube or the notochord from early chick embryos (ED 2) induces myogenesis in unspecified somites (Hamburger and Hamilton (HH) stages 11-14) when these tissues are separated by a 0.2- or a 0.05-μm pore filter. The ventral neural tube is found to be a strong inducer of myogenesis, while the dorsal neural tube is found to have low inducing activity. The reduced myogenic inducing activity of the dorsal neural tube is associated with an activity that inhibits myogenic differentiation in specified somites, somites containing cells already committed to myogenesis. Only 6-8 hr of transfilter exposure to neural tube is required to initiate somite myogenesis that is sustained in the absence of neural tube. Other tissues such as specified somites, heart, or ectoderm from the same aged embryo do not induce myogenesis in unspecified somites. Removal of the prospective floor plate of the caudal neural plate at HH stage 8 or 9 does not eliminate the inducing activity of the neurectoderm on unspecified somites (HH stage 11-14). Recombination of somites with neural tube or spinal cord from progressively older embryos (ED 4-20) showed myogenesis inducing activity at all ages, though the activity waned as development proceeded. Paraxial mesoderm need not segment into somites to respond to the inducing activity of the neural tube. We conclude that induction of myogenesis in somites does not require cell-cell contact between either the neural tube or the notochord and therefore induction is mediated by diffusible factor(s); that the inducing activity is localized principally to the notochord and ventral half of the neural tube, but not necessarily to the floor plate; that the myogenic response is specific to neural tube and notochord; and that the dorsal neural tube weakly induces myogenesis and contains an activity that inhibits myogenic cells from differentiating.