Clements J R, Beitz A J, Fletcher T F, Mullett M A
J Comp Neurol. 1985 Jun 1;236(1):60-70. doi: 10.1002/cne.902360106.
The distribution of serotonin-like immunoreactivity in five regions of the rodent midbrain periaqueductal gray (PAG) was studied by using light and electron microscopic immunohistochemistry in combination with quantitative analysis. Light microscopic analysis revealed the presence of serotonin-like immunoreactive cell bodies located in the ventrolateral and ventromedial regions of the caudal PAG and serotonin-like immunoreactive processes throughout the PAG. Ultrastructural analysis showed dendritic profiles that stained positively for serotonin primarily in ventral regions, although an occasional profile was seen dorsally. Numerous synaptic contacts between unstained axon terminals and ventral dendritic profiles were seen. Axonal profiles that contained reaction product were identified throughout the PAG, but were rarely observed to make any type of specialized contact. Ultrastructural quantification of serotonin-like immunoreactive processes indicated that the highest volume fraction of serotonin immunoreactivity occurred caudoventrally where stained processes constituted 2.6% of the neuropil volume. Rostroventrally stained processes constituted only 0.14% of the neuropil volume at the level of the posterior commissure. By contrast the amount of serotonin-like immunoreactivity found dorsally remained relatively constant at all rostrocaudal levels. Analysis of serotonin staining among PAG regions demonstrated the lowest overall volume fraction in the dorsal region and the highest overall volume fraction in the ventromedial region. No significant differences were observed between medial and lateral regions. A comparison of the results of light microscopic quantitative analysis of serotoninergic processes with electron microscopic quantitative analysis indicated that both techniques produce comparable results.
运用光镜和电镜免疫组织化学技术并结合定量分析，研究了啮齿动物中脑导水管周围灰质（PAG）五个区域中5-羟色胺样免疫反应性的分布。光镜分析显示，5-羟色胺样免疫反应性细胞体位于尾侧PAG的腹外侧和腹内侧区域，且5-羟色胺样免疫反应性神经突起遍布整个PAG。超微结构分析表明，主要在腹侧区域可见对5-羟色胺呈阳性染色的树突轮廓，尽管在背侧偶尔也能看到。可见未染色的轴突终末与腹侧树突轮廓之间有大量突触联系。在整个PAG中均发现含有反应产物的轴突轮廓，但很少观察到它们形成任何类型的特殊联系。对5-羟色胺样免疫反应性神经突起的超微结构定量分析表明，5-羟色胺免疫反应性的最高体积分数出现在尾腹侧，此处染色的神经突起占神经毡体积的2.6%。在视交叉后水平，嘴腹侧染色的神经突起仅占神经毡体积的0.14%。相比之下，在所有嘴尾水平上，背侧发现的5-羟色胺样免疫反应性数量相对恒定。PAG各区域之间5-羟色胺染色分析表明，背侧区域的总体积分数最低，腹内侧区域的总体积分数最高。在内侧和外侧区域之间未观察到显著差异。对5-羟色胺能神经突起的光镜定量分析结果与电镜定量分析结果的比较表明，两种技术产生的结果具有可比性。
