Pollard J, Eldred W D
Department of Biology, Boston University, MA 02215.
J Neurocytol. 1990 Feb;19(1):53-66. doi: 10.1007/BF01188439.
This study examined amacrine cells in the retina of the turtle Pseudemys scripta elegans, which were labelled using an antiserum directed against tyrosine hydroxylase (an enzyme participating in catecholamine synthesis). These cells were investigated using both light and electron microscopy. Labelled somata were located in the inner nuclear layer near the border of the inner plexiform layer. The dendritic arborizations of these neurons were tristratified and arborized in strata 1 and 3 and near the border between strata 4 and 5. Serial tangential sections taken through the entire inner plexiform layer of a 1 mm-2 region in mid-peripheral retina were examined. All of the synapses associated with labelled profiles were counted and classified. The majority (84%) of the synapses involving labelled processes represented output, while the remaining 16% represented synaptic input. The synaptic output of the labelled processes was as follows: 87% onto unlabelled amacrine cells, 4% onto ganglion cells, 9% onto unidentified cell processes. None of the synaptic output from labelled processes was onto bipolar cells. The synaptic input to these labelled cells was from bipolar cells (29%) and from unlabelled amacrine cells (71%). A well labelled amacrine cell was serially sectioned and examined at the ultrastructural level to analyze its synaptic connectivity. Immunoreaction product was located diffusely throughout the cytoplasm and in large vesicles. The synaptic organization of the cell was directed primarily toward output. The labelled processes were postsynaptic and presynaptic to unlabelled amacrine cell processes in strata 1 and 3 and at the border between strata 4 and 5. Synaptic input from bipolar cells was seen exclusively near the border between strata 4 and 5. Labelled processes were presynaptic to ganglion cell processes in stratum 1 and at the border between strata 4 and 5, but not in stratum 3. Quantitative studies suggested that amacrine cell inputs and outputs were evenly distributed across the dendritic arborization, while bipolar cell inputs and outputs to ganglion cells were concentrated on the distal parts of the dendritic arborization. No labelled processes were seen in the outer plexiform layer, indicating that the cells with tyrosine hydroxylase-like immunoreactivity in the turtle retina were true amacrine cells and not interplexiform cells.
本研究对秀丽锦龟视网膜中的无长突细胞进行了检测，这些细胞是用针对酪氨酸羟化酶（一种参与儿茶酚胺合成的酶）的抗血清标记的。使用光学显微镜和电子显微镜对这些细胞进行了研究。标记的胞体位于内核层靠近内网状层边界处。这些神经元的树突分支呈三层状，分布于第1层和第3层以及第4层和第5层之间的边界附近。对取自视网膜中周部1平方毫米区域的整个内网状层的连续切线切片进行了检查。对与标记轮廓相关的所有突触进行了计数和分类。涉及标记突起的突触中，大多数（84%）代表输出，其余16%代表突触输入。标记突起的突触输出如下：87%作用于未标记的无长突细胞，4%作用于神经节细胞，9%作用于未识别的细胞突起。标记突起的突触输出没有作用于双极细胞的。这些标记细胞的突触输入来自双极细胞（29%）和未标记的无长突细胞（71%）。对一个标记良好的无长突细胞进行连续切片并在超微结构水平上进行检查，以分析其突触连接性。免疫反应产物弥漫性地分布于整个细胞质和大囊泡中。该细胞的突触组织主要指向输出。在第1层和第3层以及第4层和第5层之间的边界处，标记突起对未标记的无长突细胞突起是突触后和突触前的。双极细胞的突触输入仅见于第4层和第5层之间的边界附近。在第1层以及第4层和第5层之间的边界处，标记突起对神经节细胞突起是突触前的，但在第3层不是。定量研究表明，无长突细胞的输入和输出在树突分支上均匀分布，而双极细胞对神经节细胞的输入和输出集中在树突分支的远端部分。在外网状层未见标记突起，这表明龟视网膜中具有酪氨酸羟化酶样免疫反应性的细胞是真正的无长突细胞，而非网间细胞。
