Ochi J, Yamamoto T, Hosoya Y
Arch Histol Jpn. 1979 Jul;42(3):327-36. doi: 10.1679/aohc1950.42.327.
Spinal cords of the lamprey and hagfish were fluorescence histochemically and electron microscopically examined. Ventrally to the central canal of both cyclostomes, yellow fluorescence bound to small to medium sized neurons was observed. In the lamprey only, weakly blue-green fluorescent subependymal cells were seen just beneath the central canal. In the ventral floor of their spinal cord, yellow fluorescent varicosities were observed; their density was much higher in the lamprey than in the hagfish. The lateral surface of the hagfish spinal cord was marginated by a chain of yellow fluorescent varicosities. The yellow fluorescence was microspectrofluorometrically identified as fluorescence due to 5-HT. Electron microscopically, the 5-HT neurons contained many large dense-core vesicles. The 5-HT varicosities or terminals seen in the ventral zone of both cyclostomes possessed the large dense-core vesicles and small clear synaptic vesicles, which appeared as small dense-core vesicles after KMnO4 fixation. The terminal of the lamprey was nakedly situated on the ventral surface, while that of the hagfish was always covered by the superficial glial layer. This finding seems to favor the view that lamprey and hagfish should be divided into two different classes.
对七鳃鳗和盲鳗的脊髓进行了荧光组织化学和电子显微镜检查。在这两种圆口纲动物中央管的腹侧，观察到与中小型神经元结合的黄色荧光。仅在七鳃鳗中，在中央管下方可见弱蓝绿色荧光的室管膜下细胞。在它们脊髓的腹侧底部，观察到黄色荧光的曲张体；七鳃鳗中其密度比盲鳗高得多。盲鳗脊髓的外侧表面由一串黄色荧光的曲张体界定。黄色荧光经显微分光荧光测定法鉴定为5-羟色胺引起的荧光。在电子显微镜下，5-羟色胺神经元含有许多大的致密核心囊泡。在两种圆口纲动物腹侧区所见的5-羟色胺曲张体或终末具有大的致密核心囊泡和小的清亮突触囊泡，在高锰酸钾固定后这些小的清亮突触囊泡呈现为小的致密核心囊泡。七鳃鳗的终末裸露地位于腹侧表面，而盲鳗的终末总是被表面神经胶质层覆盖。这一发现似乎支持将七鳃鳗和盲鳗分为两个不同类别的观点。
