Kolb H, Nelson R
Department of Physiology, University of Utah School of Medicine, Salt Lake City 84108.
J Comp Neurol. 1993 Mar 1;329(1):85-110. doi: 10.1002/cne.903290107.
An OFF-center alpha and an OFF-center beta ganglion cell in cat retina, which had been recorded from and intracellularly stained with horseradish peroxidase (HRP) were examined by serial section electron microscopy. We counted synapses and identified presynaptic neurons to the HRP-stained cells in 20 microns radial slices through the centers of their dendritic trees. Presynaptic amacrine and bipolar cells were identified on cytological criteria known from previous studies. The OFF-beta cell with a 62 microns dendritic arbor, restricted to S1 and S2 (sublamina a) of the inner plexiform layer (IPL), received 38% bipolar and 62% amacrine cell synapses. The bipolar input was from both cb1 and cb2 cone bipolar types. Input from three distinct amacrine cell types occurred upon the dendrites, namely from: (1) AII amacrine lobular appendages, (2) large pale amacrine profiles (possibly A2 or A3 cells), and (3) small, dark amacrine types (possibly A8 cells). Large pale amacrine profiles (possibly A13) were found on the cell body and apical dendrite in sublamina b of the IPL. In addition, several amacrine profiles synapsed directly on the sides and base of the cell body in the ganglion cell layer. We estimate that the complete dendritic tree of this beta cell received about 1,000 synapses contributed by 12-14 bipolar cells, 7-10 AII amacrines and 28-41 other amacrine cells. The OFF-alpha cell had a dendritic tree size of 680 x 920 microns. A 250 microns length of two major dendrites stratifying narrowly in S2 of the IPL was reconstructed. Amacrine cells provided most of the synaptic input (80%). This input came from: (1) AII amacrine lobular appendages, (2) amacrines exhibiting large, pale synaptic profiles (possibly A2 or A3 cells), (3) pale amacrines with large mitochondria and a few neurotubules (unknown type), and (4) densely neurotubule-filled amacrine profiles (possibly A19 cells). A large pale amacrine cell type (possibly A13) provided synaptic input to the cell body as a serial synaptic intermediary with rod bipolar cells. Cone bipolar synapses were from only one type of cone bipolar, the cb2 type and formed 20% of the total synaptic input. We estimate that a minimum of 142 bipolar cells, 256 AII amacrine cells and 1,011 other amacrine cells, altogether providing 6,000-10,000 synapses, converged on the dendritic tree of this OFF-alpha cell.
对猫视网膜中的一个离中心α和一个离中心β神经节细胞进行了研究，这两个细胞已被记录并通过辣根过氧化物酶（HRP）进行细胞内染色，随后通过连续切片电子显微镜进行检查。我们在穿过其树突树中心的20微米径向切片中，对与HRP染色细胞形成突触的突触和突触前神经元进行了计数。根据先前研究已知的细胞学标准，确定了突触前无长突细胞和双极细胞。离中心β细胞的树突 Arbor 为62微米，局限于内网状层（IPL）的S1和S2（亚层a），其接受38%的双极细胞突触和62%的无长突细胞突触。双极输入来自cb1和cb2两种视锥双极细胞类型。三种不同类型的无长突细胞的输入出现在树突上，即来自：（1）AII无长突细胞的小叶附属物，（2）大的浅色无长突细胞轮廓（可能是A2或A3细胞），以及（3）小的深色无长突细胞类型（可能是A8细胞）。在IPL亚层b的细胞体和顶端树突上发现了大的浅色无长突细胞轮廓（可能是A13）。此外，在神经节细胞层中，几个无长突细胞轮廓直接与细胞体的侧面和基部形成突触。我们估计，这个β细胞的完整树突树接受了约1000个突触，这些突触由12 - 14个双极细胞、7 - 10个AII无长突细胞和28 - 41个其他无长突细胞提供。离中心α细胞的树突树大小为680×920微米。重建了在IPL的S2中狭窄分层的两个主要树突的250微米长度。无长突细胞提供了大部分突触输入（80%）。这种输入来自：（1）AII无长突细胞的小叶附属物，（2）呈现大的浅色突触轮廓的无长突细胞（可能是A2或A3细胞），（3）具有大线粒体和少量神经微管的浅色无长突细胞（未知类型），以及（4）充满密集神经微管的无长突细胞轮廓（可能是A19细胞）。一种大的浅色无长突细胞类型（可能是A13）作为与视杆双极细胞的连续突触中介，为细胞体提供突触输入。视锥双极突触仅来自一种视锥双极细胞，即cb2类型，占总突触输入的20%。我们估计，至少142个双极细胞、256个AII无长突细胞和1011个其他无长突细胞，总共提供6000 - 10000个突触，汇聚在这个离中心α细胞的树突树上。
