Freed M A, Sterling P
University of Pennsylvania Medical School, Department of Anatomy, Philadelphia 19104.
J Neurosci. 1988 Jul;8(7):2303-20. doi: 10.1523/JNEUROSCI.08-07-02303.1988.
Anatomical circuits converging onto the ON-alpha (Y) ganglion cell were studied by computer-assisted reconstruction of substantial portions of 2 alpha cells from electron micrographs of serial sections. The alpha cells in the area centralis were labeled by a Golgi-like retrograde filling with horseradish peroxidase, and certain presynaptic amacrine processes were labeled by uptake of 3H-glycine. About 4400 synapses contacted the alpha cell. Eighty-six percent were from amacrine cells; the rest were from bipolar cells. About one-quarter of the amacrine synapses were specifically labeled by 3H-glycine and probably belong to the A4 amacrine. The bipolar inputs were provided by several types: cone bipolar CBb1 (85%), cone bipolar CBb5 (2%), the rod bipolar (5%), and some unidentified cone bipolars (11%). Contacts from each type occurred in specific strata, with the consequence that they tended to form spots or annulli over the alpha dendritic field. The CBb1 bipolars formed a moderately dense array (8000/mm2), with a nearest-neighbor distance of 8.6 +/- 1.3 microns. Most members of the array (84%) contacted the alpha cell, providing 1-7 synapses (average, 2.7 +/- 1.6). The placement of contacts from an individual CBb1 followed certain rules: they were restricted to a parent branch of the alpha arbor or to 2 daughter branches, but almost never crossed a branch of the alpha arbor. The synaptic territory of an individual CBb1 was not shared with other b1s (or cone bipolars of any sort), although it was shared with amacrine contacts. Rod bipolar cells also formed a very dense array (54,500/mm2) in the alpha dendritic field, but only a few of these (3%) contacted the alpha cell. The concentric receptive field of the CBb1, combined with the spatial organization of its array, is used to predict the CBb1 contribution to the alpha cell receptive field; this contribution resembles the spatial and temporal organization of the alpha receptive field itself.
通过对连续切片电子显微照片中2个α细胞的大部分进行计算机辅助重建，研究了汇聚到ON-α（Y）神经节细胞的解剖学回路。用类似高尔基染色法的辣根过氧化物酶逆行填充标记中央凹区域的α细胞，通过摄取³H-甘氨酸标记某些突触前无长突细胞的突起。约4400个突触与α细胞接触。86%来自无长突细胞；其余来自双极细胞。约四分之一的无长突细胞突触被³H-甘氨酸特异性标记，可能属于A4无长突细胞。双极细胞的输入有几种类型：视锥双极细胞CBb1（85%）、视锥双极细胞CBb5（2%）、视杆双极细胞（5%）和一些未鉴定的视锥双极细胞（11%）。每种类型的接触发生在特定的层，结果是它们倾向于在α树突野上形成斑点或环。CBb1双极细胞形成中等密度的阵列（8000/mm²），最近邻距离为8.6±1.3微米。阵列中的大多数成员（84%）与α细胞接触，提供1 - 7个突触（平均为2.7±1.6个）。单个CBb1的接触位置遵循一定规则：它们局限于α树突的一个母分支或两个子分支，但几乎从不跨越α树突的分支。单个CBb1的突触区域不与其他b1（或任何类型的视锥双极细胞）共享，尽管它与无长突细胞的接触共享。视杆双极细胞在α树突野中也形成非常密集的阵列（54500/mm²），但其中只有少数（3%）与α细胞接触。CBb1的同心感受野及其阵列的空间组织，用于预测CBb1对α细胞感受野的贡献；这种贡献类似于α感受野本身的空间和时间组织。
