FORMATION OF THE TRANSVERSE NERVE IN MOTH EMBRYOS .2. STEREOTYPED GROWTH BY THE AXONS OF IDENTIFIED NEURO-ENDOCRINE NEURONS
FORMATION OF THE TRANSVERSE NERVE IN MOTH EMBRYOS .2. STEREOTYPED GROWTH BY THE AXONS OF IDENTIFIED NEURO-ENDOCRINE NEURONS
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DOI：
10.1016/0012-1606(88)90345-4
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发表时间：
1988-12-01
影响因子：
2.7
通讯作者：
TAGHERT, PH
中科院分区：
文献类型：
--
作者：
CARR, JN;TAGHERT, PH
我们对引导神经内分泌轴突到达神经血液目标区域并调节其末端乔木的范围和位置的细胞机制感兴趣。我们研究的神经血液器官是天蛾的节段重复横神经。在成熟的动物中，两个运动神经元和一组已识别的异质神经内分泌神经元投射到该神经；后者沿着其长度释放激素肽。在之前的报告中，我们证明了在胚胎发生过程中，横神经的位置、轨迹和范围是由两组非神经元细胞（带和桥）预测的。在本文中，我们展示了四个已识别的神经内分泌神经元（L1 和 B1-3），就像之前已识别的运动神经元一样，精心设计了生长锥，使用这种预先存在的支架作为轴突伸长的基质。此外，这些神经内分泌神经元的生长锥导航与运动神经元所显示的一样精确且不变。将发育中的神经内分泌细胞的行为与运动神经元的行为区分开来的一个特征是 L1 和 B1-3 轴突与紧邻带子的已识别合胞体细胞进行的刻板相互作用。每个神经内分泌神经元通过在合胞体表面延伸大量的丝状伪足和偶尔的大板状伪足来特异性地粘附在合胞体上。在神经内分泌轴突的生长锥离开合胞体附近并进入带/桥复合体后，这些接触由神经内分泌轴突维持。对合胞体的粘附是短暂的，并且对神经内分泌神经元具有特异性：尽管运动神经元轴突同时存在于同一时间和地点，但它们对合胞体没有亲和力。这种区别与以下事实相关：神经内分泌神经元在横神经的范围内继续形成乔木，而运动神经元则不然。我们认为合胞体可能充当这些神经元的“虚构目标”，以帮助区分其细胞表型特有的特征。
We are interested in the cellular mechanisms that guide neuroendocrine axons to their neurohaemal target regions and that regulate the extent and positioning of their terminal arbor. The neurohaemal organ we have studied is the segmentally repeated transverse nerve of the moth Manduca. In the mature animal, two motor neurons and a heterogeneous set of identified neuroendocrine neurons project to this nerve; the latter release hormonal peptides from along its length. In the preceding report, we demonstrated that during embryogenesis, the position, trajectory and extent of the transverse nerve are anticipated by two sets of nonneuronal cells, the strap and the bridge. In this paper we show that four identified neuroendocrine neurons (L1 and B1-3), like the identified motor neurons before them, elaborate growth cones that use this preexisting scaffolding as a substrate for axonal elongation. Moreover, growth cone navigation by these neuroendocrine neurons is as precise and invariant as that displayed by the motor neurons. One feature that differentiates the behavior of the developing neuroendocrine cells from that of the motor neurons is a stereotyped interaction that the L1 and B1-3 axons undergo with an identified syncytial cell that lies in close proximity to the strap. Each neuroendocrine neuron specifically adheres to the syncytium by extending numerous filopodia, and an occasional large lamellopodium, over its surface. These contacts are maintained by the neuroendocrine axons after their growth cones have left the vicinity of the syncytium and proceeded into the strap/bridge complex. Adhesion to the syncytium is transient and specific to the neuroendocrine neurons: although motor neuron axons are present at this same time and place, they display no affinity for the syncytium. This distinction correlates with the fact that the neuroendocrine neurons go on to elaborate arbor within the confines of the transverse nerve, while the motor neurons do no. We suggest that the syncytium may act as a "fictive target" for these neurons to aid in the differentiation of features that are specific to their cellular phenotype.