Gillon J W, Wallace B G
J Comp Neurol. 1984 Sep 1;228(1):142-8. doi: 10.1002/cne.902280113.
Mechanosensory and motor neurons in the central nervous system of the leech have been examined by intracellular injection of horseradish peroxidase and electrophysiological mapping of their peripheral fields to determine how the arborizations of homologous cells are influenced by their segmental position. The branching patterns of annulus erector (AE) motoneurons in ganglia near the head and tail were found to be more extensive than those of cells in midbody ganglia. As in midbody ganglia, the peripheral fields of AE motoneurons in adjacent ganglia near the head and tail overlapped extensively, but the subfields innervated by individual branches of a single AE motoneuron showed little or no overlap. No AE motoneurons were found in the head ganglion or in the 20th and 21st free segmental ganglia. The branching pattern of touch-sensitive mechanosensory cells showed a similar segmental variation; touch cells in ganglia near the head and tail had more extensive arborizations than those in midbody ganglia. The rostrocaudal position along the cord at which the branching pattern changed from that characteristic of midbody ganglia to one with a more extensive arborization differed for different types of neurons. These findings demonstrate that a cell's pattern of arborization is not determined by a simple segmental difference between ganglia and suggest that during development neurons respond individually to cues that vary along the length of the cord.
通过向水蛭中枢神经系统中的机械感觉神经元和运动神经元内注射辣根过氧化物酶，并对其外周场进行电生理图谱分析，以确定同源细胞的树突分支如何受其节段位置的影响。结果发现，靠近头部和尾部神经节的环肌运动神经元（AE）的分支模式比中体神经节中的细胞更为广泛。与中体神经节一样，靠近头部和尾部的相邻神经节中AE运动神经元的外周场广泛重叠，但单个AE运动神经元的各个分支所支配的子场几乎没有重叠。在头部神经节或第20和21个游离节段神经节中未发现AE运动神经元。触觉敏感机械感觉细胞的分支模式也表现出类似的节段变化；靠近头部和尾部神经节中的触觉细胞比中体神经节中的触觉细胞具有更广泛的树突分支。不同类型的神经元从具有中体神经节特征的分支模式转变为具有更广泛树突分支模式的沿脊髓的头尾位置有所不同。这些发现表明，细胞的树突分支模式不是由神经节之间简单的节段差异决定的，这表明在发育过程中，神经元会分别对沿脊髓长度变化的线索做出反应。
