Horn J P, Stofer W D
Department of Physiology, University of Pittsburgh School of Medicine, Pennsylvania 15261.
J Comp Neurol. 1988 Feb 1;268(1):71-83. doi: 10.1002/cne.902680108.
These experiments were designed to characterize the distribution, morphology, and number of spinal preganglionic neurons that selectively innervate the B- and C-type sympathetic neurons in paravertebral ganglia 9 and 10 of the bullfrog. For this purpose, horseradish peroxidase (HRP) was applied to the anterior end of the sectioned sympathetic chain between ganglia 8 and 9. Subsequent retrograde axonal transport of the HRP labeled ipsilateral spinal neurons whose cell bodies form a column having rostral and caudal boundaries that are, respectively, just caudal to the level of spinal nerve 4 and midway between the entry zones of spinal nerves 7 and 8. In all segments, the labeled preganglionic somata were found in the lateral half of the spinal gray and slightly dorsal to the central canal; a position analogous to that of the intermediolateral cell column in mammals. Most labeled preganglionic neurons were multipolar in shape, and the cell bodies lying between spinal nerves 4 and 5 were, on average, larger than those found between spinal nerves 7 and 8. In transverse sections that were cut near spinal nerve 5, the axons of preganglionic neurons could be seen to exit the cord through ventral roots. Counts of labeled preganglionic neurons indicate that an average +/- S.D. of 338 +/- 89 cells innervate ganglia 9 and 10. Selective labeling of preganglionic B neurons, by cutting spinal nerves 7 and 8 central to their rami communicantes at the time of HRP application, revealed an average +/- S.D. of 137 +/- 31 cells that lie exclusively between spinal nerves 4 and 6. By contrast, selective labeling of preganglionic C neurons, by cutting the sympathetic chain rostral to ganglion 7 at the time of HRP application, revealed an average +/- S.D. of 187 +/- 77 cells in an adjacent portion of the preganglionic column that is bounded by spinal nerve 6 and by a point midway between spinal nerves 7 and 8. These results thus demonstrate a clear segmental segregation between the preganglionic B and C neurons that innervate ganglia 9 and 10.
这些实验旨在描述选择性支配牛蛙第9和第10交感神经节中B型和C型交感神经元的脊髓节前神经元的分布、形态和数量。为此，将辣根过氧化物酶（HRP）应用于第8和第9神经节之间切断的交感神经链的前端。随后，HRP逆行轴突运输标记同侧脊髓神经元，其细胞体形成一个柱状结构，其头端和尾端边界分别恰好在第4脊神经水平的尾侧以及第7和第8脊神经进入区之间的中点。在所有节段中，标记的节前神经元胞体位于脊髓灰质的外侧半部分且略高于中央管；这一位置类似于哺乳动物的中间外侧细胞柱。大多数标记的节前神经元呈多极形，位于第4和第5脊神经之间的细胞体平均比位于第7和第8脊神经之间的细胞体大。在靠近第5脊神经处横切的切片中，可以看到节前神经元的轴突通过腹根离开脊髓。标记的节前神经元计数表明，平均±标准差为338±89个细胞支配第9和第10神经节。在应用HRP时，通过在其交通支的中央切断第7和第8脊神经来选择性标记节前B神经元，结果显示平均±标准差为137±31个细胞，它们仅位于第4和第6脊神经之间。相比之下，在应用HRP时，通过在第7神经节头端切断交感神经链来选择性标记节前C神经元，结果显示在节前柱的相邻部分平均±标准差为187±77个细胞，该部分由第6脊神经以及第7和第8脊神经之间中点界定。因此，这些结果清楚地表明支配第9和第10神经节的节前B和C神经元之间存在明显的节段性分离。
