Gábriel R, Zhu B, Straznicky C
Department of Anatomy and Histology, School of Medicine, Flinders University of South Australia, Adelaide, Australia.
Cell Tissue Res. 1992 Mar;267(3):525-34. doi: 10.1007/BF00319375.
Tyrosine hydroxylase (TH) immunocytochemistry was utilized to quantify dopaminergic synapses in the inner plexiform layer of the retina of Bufo marinus. Since dopaminergic cells have bistratified dendritic arborisation in the inner plexiform layer, attention was given to the segregation of synapses between the scleral and the vitreal sublaminae. Light-microscopically, a more elaborate dendritic branching was observed in the scleral than in the vitreal sublamina. In contrast, about 55% of synapses occurred in the vitreal one fifth of the inner plexiform layer, 30% in the scleral fifth, and 15% in the intermediate laminae. Input sources and output targets showed only minor quantitative differences between sublaminae 1 and 5. TH-immunoreactive processes were found in presynaptic (62.8%) and postsynaptic (37.2%) positions. Synapses to the stained dendrites derived from bipolar (40.4%) and amacrine (59.6%) cells, whereas outputs from the TH-positive processes were directed to amacrine cells (56.8%) and to small and medium-sized dendrites (35.4%); at least some of these can be considered as ganglion cell dendrites. TH-positive profiles neither formed synapses with each other nor were presynaptic to bipolar cell terminals. Junctional appositions of the immunoreactive profiles were occasionally seen on non-stained amacrine and ganglion cell dendrites in the scleral sublamina of the inner plexiform layer and on optic axons in the optic fibre layer. Although dopaminergic cells are mainly involved in amacrine-amacrine interactions, inputs from bipolar terminals and outputs to ganglion cell dendrites were also substantial, suggestive of a role also in vertical information processing.
利用酪氨酸羟化酶（TH）免疫细胞化学技术对海蟾蜍视网膜内丛状层中的多巴胺能突触进行定量分析。由于多巴胺能细胞在内丛状层具有双分层树突分支，因此关注巩膜和玻璃体亚层之间突触的分离情况。在光学显微镜下，巩膜亚层中的树突分支比玻璃体亚层更为复杂。相比之下，约55%的突触出现在内丛状层玻璃体侧的五分之一区域，30%在巩膜侧的五分之一区域，15%在中间层。输入源和输出靶点在亚层1和5之间仅显示出微小的数量差异。TH免疫反应性过程出现在突触前（62.8%）和突触后（37.2%）位置。与染色树突形成突触的来源于双极细胞（40.4%）和无长突细胞（59.6%），而TH阳性过程的输出则指向无长突细胞（56.8%）和中小尺寸树突（35.4%）；其中至少一些可被视为神经节细胞树突。TH阳性结构既不相互形成突触，也不是双极细胞终末的突触前结构。免疫反应性结构的连接并置偶尔可见于内丛状层巩膜亚层中未染色的无长突细胞和神经节细胞树突以及视神经纤维层中的视神经轴突上。尽管多巴胺能细胞主要参与无长突细胞-无长突细胞相互作用，但来自双极终末的输入和到神经节细胞树突的输出也很显著，提示其在垂直信息处理中也发挥作用。
