King J S, Ho R H, Burry R W
J Comp Neurol. 1984 Aug 10;227(3):357-68. doi: 10.1002/cne.902270306.
Immunohistochemistry and high-resolution autoradiography were used to analyze the distribution and synaptic organization of serotonin (5HT) - containing elements in the inferior olivary complex of the opossum. Immunoreactive beaded varicosities are present throughout the olivary complex. The densest 5HT immunostaining is present in subnucleus b of the caudal medial accessory nucleus. The rostral principal olive is sparsely populated with immunoreactive elements. Fine beaded fibers arborize throughout the neuropil of all the olivary nuclei except in subnucleus b of the caudal medial accessory nucleus where they also circumscribe neuronal cell bodies. In addition, a distinct population of large beaded fibers are occasionally encountered in the neuropil of the medial accessory nucleus. Ultrastructurally, labeled profiles that correspond in size to the smaller beads (less than 1 micron) contain tubulovesicular elements, large dense-cored vesicles, and clear vesicles. In contrast, larger profiles (greater than 2 microns) are characterized by numerous clear synaptic vesicles. Synaptic junctions were encountered in only 2% of the labeled elements. The majority of the labeled profiles were in juxtaposition to small-diameter dendrites (less than 2 microns) except in the caudal medial accessory nucleus, where they also were found in apposition to olivary cell bodies. Our results, when compared with other accounts, indicate that rather than major differences in the nuclear distribution of serotonin between species, there are differences in the density of serotoninergic elements in specific nuclei of the mammalian inferior olive. Based on the size of the labeled profiles and the distinct vesicle populations, our data suggest there are at least two populations of 5HT varicosities that are in juxtaposition to olivary neurons. Further, boutons containing 5HT primarily interact with the distal dendrites of olivary neurons except in the caudal medial accessory nucleus where cell bodies are in apposition to 5HT varicosities.
免疫组织化学和高分辨率放射自显影技术被用于分析负鼠下橄榄复合体中含5-羟色胺（5HT）元素的分布和突触组织。整个橄榄复合体内均存在免疫反应性串珠状膨体。尾侧内侧副核的b亚核中5HT免疫染色最为密集。吻侧主橄榄核中免疫反应性元素分布稀疏。细的串珠状纤维在所有橄榄核的神经毡中呈树枝状分布，但在尾侧内侧副核的b亚核中除外，在该亚核中它们也围绕神经元细胞体。此外，在内侧副核的神经毡中偶尔会遇到一群独特的大串珠状纤维。超微结构上，与较小串珠（小于1微米）大小相对应的标记轮廓包含微管泡状结构、大的致密核心囊泡和清亮囊泡。相比之下，较大的轮廓（大于2微米）的特征是有大量清亮突触囊泡。仅在2%的标记元素中发现了突触连接。除尾侧内侧副核外，大多数标记轮廓与小直径树突（小于2微米）并列，在尾侧内侧副核中它们也与橄榄细胞体相邻。与其他报道相比，我们的结果表明，物种间5-羟色胺在核分布上并非存在主要差异，而是在哺乳动物下橄榄核的特定核中5-羟色胺能元素的密度存在差异。根据标记轮廓的大小和不同的囊泡群体，我们的数据表明至少有两群5HT膨体与橄榄神经元并列。此外，含5HT的终扣主要与橄榄神经元的远端树突相互作用，但在尾侧内侧副核中细胞体与5HT膨体相邻。
