Song J K, Northcutt R G
Department of Biology, University of Michigan, Ann Arbor.
Brain Behav Evol. 1991;37(1):38-63. doi: 10.1159/000114345.
Gars, like most other ray-finned fishes, possess lines of superficial and canal neuromasts that form highly ordered spatial arrays on the head and trunk. These neuromasts are innervated by three pairs of cranial nerves: anterior, middle and posterior lateral-line nerves. Application of horseradish peroxidase to the roots of these nerves indicates that the afferent fibers of each nerve terminate throughout the rostrocaudal extent of the ipsilateral octavolateralis column, composed of medial and caudal octavolateralis nuclei, as well as rostrally in the eminentia granularis of the cerebellum. The afferents of each nerve terminate within different regions of these nuclei, thus preserving a rostrocaudal somatotopy of the peripheral receptors. The individual rami of these nerves innervate peripheral receptors in a dorsoventral sequence; however, application of horseradish peroxidase to these rami indicates an almost total overlap of the terminal fields of adjacent rami and, thus, little or no preservation of dorsoventral somatotopy of the peripheral receptors. Similarly, the terminal fields of fibers that innervate canal and superficial neuromasts overlap extensively, and there is no evidence for separate maps of canal and superficial neuromasts. Furthermore, the position of the terminal fields of superficial neuromasts is not consistent with a hypothesis that these receptors may have evolved into electroreceptors in some teleosts. However, these experiments do indicate that superficial neuromasts, like canal neuromasts, are innervated by efferent fibers of rostral and caudal efferent nuclei, but there is no evidence of a diencephalic efferent nucleus as occurs in teleosts.
与大多数其他硬骨鱼一样，雀鳝拥有体表神经丘和管道神经丘线，它们在头部和躯干上形成高度有序的空间阵列。这些神经丘由三对脑神经支配：前侧线神经、中间侧线神经和后侧线神经。将辣根过氧化物酶应用于这些神经的根部表明，每条神经的传入纤维在同侧八侧线柱的整个前后范围内终止，该八侧线柱由内侧和尾侧八侧线核组成，并且在小脑的颗粒隆起处向前延伸。每条神经的传入纤维在这些核的不同区域内终止，从而保留了外周感受器的前后躯体定位。这些神经的各个分支按背腹顺序支配外周感受器；然而，将辣根过氧化物酶应用于这些分支表明相邻分支的终末场几乎完全重叠，因此外周感受器的背腹躯体定位几乎没有保留。同样，支配管道神经丘和体表神经丘的纤维的终末场广泛重叠，没有证据表明管道神经丘和体表神经丘有单独的图谱。此外，体表神经丘终末场的位置与这样一种假设不一致，即这些感受器在某些硬骨鱼中可能已经进化为电感受器。然而，这些实验确实表明，体表神经丘与管道神经丘一样，由吻侧和尾侧传出核的传出纤维支配，但没有证据表明存在硬骨鱼中出现的间脑传出核。
