Mohr C, Görner P
University of Bielefeld, Department of Biology II, Germany.
Brain Behav Evol. 1996;48(2):55-69. doi: 10.1159/000113186.
We quantitatively examined the afferent innervation pattern of the lateral line stitches of both larval and postmetamorphotic clawed frogs, Xenopus laevis, using a silver staining technique. We also studied the relevance of the number of neuromasts in a stitch to physiological properties, recording afferent activity with an electrode inserted directly into the neuromast. The innervation pattern changed during early metamorphosis, the fiber thickness increasing after the reorganization. We found three different innervation patterns: in type A stitches, the same two afferent fibers innervate all neuromasts; in type B stitches, one or two fibers innervate more than one stitch; in type C stitches, three to six fibers innervate a stitch. The distribution of the different types of stitches varied in different parts of the body. The frequency of type A stitches differed between larval trunk and larval head. For both larvae and juveniles, type B stitches were more frequent on ventral than dorsal areas, while type C stitches were more frequent on the head than on the trunk. Electrophysiological experiments indicated that the sensitivity of an afferent fiber increases with the number of neuromasts it innervates. This increase and the variation in innervation patterns shows that the single afferent fiber, not the stitch, is the functional unit of the lateral line periphery.
我们采用银染技术，对非洲爪蟾（Xenopus laevis）幼体和成体变态后的侧线缝的传入神经支配模式进行了定量研究。我们还研究了缝中神经丘数量与生理特性的相关性，通过将电极直接插入神经丘来记录传入活动。在变态初期，神经支配模式发生了变化，重组后纤维厚度增加。我们发现了三种不同的神经支配模式：在A型缝中，相同的两条传入纤维支配所有神经丘；在B型缝中，一条或两条纤维支配多个缝；在C型缝中，三到六条纤维支配一个缝。不同类型缝的分布在身体的不同部位有所不同。幼虫躯干和幼虫头部的A型缝频率不同。对于幼虫和幼体来说，B型缝在腹部比背部更常见，而C型缝在头部比在躯干更常见。电生理实验表明，传入纤维的敏感性随着它所支配的神经丘数量的增加而增加。这种增加以及神经支配模式的变化表明，单个传入纤维而非缝是侧线外周的功能单位。
