Fitzpatrick D, Diamond I T
J Comp Neurol. 1980 Dec 15;194(4):703-19. doi: 10.1002/cne.901940402.
This inquiry began with the discovery that just two layers of the lateral geniculate nucleus (GL) of Galago contain large amounts of acetylcholinesterase (AChE). These two layers (layers 3 and 6) are similar in cell size and Nissl-staining characteristics and project to the same layer in the striate cortex. To find out whether the pattern of staining is unique in the Galago, we examined the distribution of AChE in the lateral geniculate nucleus of the owl monkey, Aotus trivirgatus. In this species we found that the parvocellular layers (3 and 4) stained darkly for AChE while the magnocellular layers (1 and 2) were only slightly stained. The interlaminar zones as well as the "S" layers were also distinguished by a high level of AChE staining. In order to determine the source of the cholinesterase staining in layers 3 and 6 of Galago, we studied, in separate experiments, the effects of kainic acid injections into GL, of eye enucleation, and of lesions of the striate cortex. Injections of kainic acid, followed by survival times of 2 and 11 days, produced severe cellular destruction in GL, yet the AChE staining of layers 3 and 6 was undiminished. Eye enucleations had no effect upon the AChE staining of GL even after a survival period of 3 years. In contrast, a small lesion of the striate cortex, followed by a 9-day survival period, produced conspicuous gaps in the AChE staining of layers 3 and 6. These results indicate that the AChE in layers 3 and 6 is not attributable to the cells within the layers, or to retinal fibers, but is dependent upon descending projections from the striate cortex. Because of the dependence of the AChE reaction product in layers 3 and 6 of GL upon an intact striate cortex, we turned our attention to the distribution of AChE in the striate cortex. In Galago, cholinesterase-positive cells were found in layer VI of the striate cortex; and in both Galago and Aotus, the striate cortex was distinguished from other cortical areas by a prominent band of cholinesterase activity within layer IV. This band ended abruptly at the 17-18 border. The precise origin of this cholinesterase staining within layer IV of the striate cortex remains to be determined.
这项研究始于发现夜猴外侧膝状核（GL）仅有两层含有大量乙酰胆碱酯酶（AChE）。这两层（第3层和第6层）在细胞大小和尼氏染色特征方面相似，并投射到纹状皮层的同一层。为了弄清楚这种染色模式在夜猴中是否独特，我们检查了三带松鼠猴（Aotus trivirgatus）外侧膝状核中AChE的分布。在这个物种中，我们发现小细胞层（第3层和第4层）AChE染色较深，而大细胞层（第1层和第2层）仅轻微染色。层间区以及“S”层也因高水平的AChE染色而得以区分。为了确定夜猴第3层和第6层中胆碱酯酶染色的来源，我们在单独的实验中研究了向GL注射 kainic 酸、摘除眼球以及损伤纹状皮层的影响。注射kainic酸后，经过2天和11天的存活期，GL中出现了严重的细胞破坏，但第3层和第6层的AChE染色并未减弱。即使经过3年的存活期，摘除眼球对GL的AChE染色也没有影响。相比之下，纹状皮层的一个小损伤，经过9天的存活期后，在第3层和第6层的AChE染色中产生了明显的间隙。这些结果表明，第3层和第6层中的AChE并非来自这些层内的细胞或视网膜纤维，而是依赖于来自纹状皮层的下行投射。由于GL第3层和第6层中AChE反应产物依赖于完整的纹状皮层，我们将注意力转向了纹状皮层中AChE的分布。在夜猴中，在纹状皮层的第VI层发现了胆碱酯酶阳性细胞；并且在夜猴和三带松鼠猴中，纹状皮层与其他皮层区域的区别在于第IV层内有一条明显的胆碱酯酶活性带。这条带在17 - 18边界处突然终止。纹状皮层第IV层内这种胆碱酯酶染色的确切来源仍有待确定。
