Wilson J R, Friedlander M J, Sherman S M
Proc R Soc Lond B Biol Sci. 1984 Jun 22;221(1225):411-36. doi: 10.1098/rspb.1984.0042.
Four physiologically identified neurons in the A laminae of the cat's dorsal lateral geniculate nucleus were filled with horseradish peroxidase and studied using the electron microscope. Two were X-cells and two were Y-cells. Each had electrophysiological properties appropriate for its X- Or Y-cell class, and each also had an axon that projected into the optic radiation, indicative of a geniculocortical relay cell. Representative samples from about 10% of each neuron's entire dendritic arbor (proximal and distal) were taken to obtain an estimate of the types and distributions of synapses contacting these arbors. One X-cell had a cytoplasmic laminar body, but there were no other significant cytological differences seen among the neurons. Common to each of the neurons were the following synaptic features: (i) retinal terminals (r.l.p.) were mostly or entirely restricted to proximal dendrites or dendritic appendages (less than 100 microns from the soma). These terminals constituted about 15-25% of the synapses on the proximal dendrites. (ii) Terminals with flattened or pleomorphic synaptic vesicles (f. terminals) were predominant on the proximal dendrites (30-55% of the total synapses for that region) and were mainly located near the retinal terminals. A smaller percentage (10-20%) were also distributed onto the distal dendrites. (iii) Small terminals with round synaptic vesicles (r.s.d.), many presumably having a cortical origin, predominated (60-80%) on distal dendrites (greater than 100 microns), but also formed a large proportion (40-70%) of the synapses on the intermediate (50-150 microns) dendrites. Total synaptic contacts for one X-cell and one Y-cell were estimated at about 4000 and 5000, respectively. The major fine structural differences observed between X- and Y-cells were almost entirely related to the retinal afferents. First, the retinal synapses for X-cells were mostly made on to dendritic appendages (spines, etc.), whereas Y-cells had most of their retinal synapses onto the shafts of primary and proximal secondary dendrites (that is, near branch points. Second, the retinal terminals that contacted X-cell dendrites nearly always formed triadic arrangements that included nearby f. terminals, but those on Y-cells rarely did so. Finally, the main type of f. terminals associated with X-cells were morphologically different from most of those associated with the Y-cells, and this also related directly to the triadic arrangements; that is, f. terminals in the triadic arrangements were morphologically distinguishable from f. terminals that did not participate in triadic arrangements.(ABSTRACT TRUNCATED AT 400 WORDS)
对猫背外侧膝状核A层中的四个经生理学鉴定的神经元进行辣根过氧化物酶填充，并用电镜进行研究。其中两个是X细胞，两个是Y细胞。每个细胞都具有适合其X或Y细胞类型的电生理特性，并且每个细胞都有一条轴突投射到视辐射中，表明是膝状体皮质中继细胞。从每个神经元整个树突分支（近端和远端）的约10%中选取代表性样本，以估计与这些分支接触的突触的类型和分布。一个X细胞有一个胞质层状小体，但在这些神经元之间未观察到其他明显的细胞学差异。每个神经元共有的突触特征如下：（i）视网膜终末（r.l.p.）大多或完全局限于近端树突或树突附属物（距胞体小于100微米）。这些终末约占近端树突上突触的15 - 25%。（ii）具有扁平或多形突触小泡的终末（f.终末）在近端树突上占主导（该区域总突触的30 - 55%），主要位于视网膜终末附近。较小比例（10 - 20%）也分布在远端树突上。（iii）具有圆形突触小泡的小终末（r.s.d.），许多可能起源于皮质，在远端树突（大于100微米）上占主导（60 - 80%），但在中间（50 - 150微米）树突上也占很大比例（40 - 70%）。估计一个X细胞和一个Y细胞的总突触接触分别约为4000和5000。在X细胞和Y细胞之间观察到的主要细微结构差异几乎完全与视网膜传入有关。首先，X细胞的视网膜突触大多形成于树突附属物（棘等）上，而Y细胞的大多数视网膜突触形成于初级和近端二级树突的轴干上（即靠近分支点）。其次，与X细胞树突接触的视网膜终末几乎总是形成三联体排列，包括附近的f.终末，但Y细胞上的视网膜终末很少如此。最后，与X细胞相关的主要f.终末类型在形态上与大多数与Y细胞相关的不同，这也直接与三联体排列有关；也就是说，三联体排列中的f.终末在形态上可与不参与三联体排列的f.终末区分开来。（摘要截断于400字）
