Developmental dynamics of functionally specific primary sensory afferent projections in the chicken embryo
Developmental dynamics of functionally specific primary sensory afferent projections in the chicken embryo
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DOI：
10.1007/s004290050043
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发表时间：
1997-03-01
期刊：
影响因子：
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通讯作者：
Glover, JC
中科院分区：
文献类型：
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作者：
Eide, AL;Glover, JC
在鸡胚固定制剂中，用亲脂示踪剂DiI选择性标记腰椎初级传入神经特定亚群的中心突起。用DiI选择性地标记肌肉或皮肤传入神经。通过部分损伤背根，选择性地标记内侧或外侧传入群。肌肉和皮肤传入神经群分别对内侧和外侧传入神经群有贡献。内侧肌传入神经在近端终止于中间区和外侧运动柱，但仅在远端终止于中间区。外侧肌传入神经在背角的腹外侧区域终止于近端和远端。内侧皮肤传入神经主要终止于III层，但少数终止于中间区的内侧区域。外侧皮肤传入神经终止于II层和背角的腹外侧区域。在基本终止模式的基础上，定义了特定的终止场，并将其与脊髓灰质的经典细胞结构联系起来。荧光右旋氨基对脊髓的差异逆行示迹表明，内侧传入信号起源于较早产生的大感觉细胞体腹外侧群体，而外侧传入信号起源于较晚产生的小感觉细胞体背内侧群体。内侧传入神经比外侧传入神经更早地形成中心突起，但对于每个亚群来说，在侧枝的整个节段范围内，初始的终止模式预示着成熟的模式。用h -3胸腺嘧啶测定出生日期表明，背角内不同终末场的潜在目标神经元在不同的时间出生。特别是，II板的中间神经元在III板之后产生，与这些板的皮肤传入神经的早期和晚期终止平行。我们的观察结果支持初级传入识别脊髓中特定线索的观点，但也暗示传入和目标分化的相对时间是初级传入终止模式的重要决定因素。
The central projections of specific subpopulations of lumbar primary afferents were selectively labeled with the lipophilic tracer DiI in fixed preparations of the chicken embryo. Muscle or cutaneous afferents were selectively labeled by applying DiI to identified peripheral nerves. Medial or lateral afferent populations were selectively labeled by partially lesioning the dorsal root. Muscle and cutaneous afferent populations each contribute to both the medial and the lateral afferent populations. Medial muscle afferents terminate in the intermediate zone and lateral motor column proximally, but only in the intermediate zone distally. Lateral muscle afferents terminate in a ventrolateral region of the dorsal horn both proximally and distally. Medial cutaneous afferents terminate predominantly in lamina III, but a few terminate in the medial region of the intermediate zone. Lateral cutaneous afferents terminate in lamina II and in a ventrolateral region of the dorsal horn. On the basis of the principle termination patterns, specific termination fields were defined and related to the classical cytoarchitectonics of the spinal gray matter. Differential retrograde tracing from the spinal cord with fluorescent dextran-amines demonstrated that the medial afferents originate from the earlier-generated ventrolateral population of large sensory cell bodies, while the lateral afferents originate from the later-generated dorsomedial population of small sensory cell bodies. The medial afferents establish their central projections earlier than the lateral afferents, but for each subpopulation the initial pattern of termination prefigures the mature pattern, throughout the segmental range of the collaterals. Birthdating with H-3-thymidine showed that potential target neurons in the different terminal fields within the dorsal horn are born at different times. In particular, interneurons in lamina II are born after those in lamina III, paralleling the early and late termination of cutaneous afferents in these laminae. Our observations support the notion that primary afferents recognize specific cues in the spinal cord, but also implicate the relative timing of afferent and target differentiation as an important determinant of primary afferent termination patterns.