Dos Santos Setsuko N, Dos Reis José Wesley L, Da Silva Filho Manoel, Kremers Jan, Silveira Luiz Carlos L
Departamento de Fisiologia, Universidade Federal do Pará, Belém, Pará Brasil.
Vis Neurosci. 2005 Jul-Aug;22(4):405-15. doi: 10.1017/S0952523805224033.
Horizontal cell morphology was studied in the retina of the nocturnal owl-monkey, Aotus, and compared with that of its diurnal, close relative, the capuchin monkey, Cebus . Cells were initially labeled with DiI and the staining was later photoconverted in a stable precipitated using DAB as chromogen. The sizes of cell bodies, dendritic fields, and axon terminals, number of dendritic clusters, intercluster spacing, and intercone spacing were measured at increasing eccentricities. Two distinct morphological classes of horizontal cells were identified, which resembled those of H1 and H3 cells described in diurnal monkeys. A few examples of a third class, possibly corresponding to the H2 cells of diurnal monkeys, were labeled. Both H1 and H3 cells increased in size and had increasing numbers of dendritic clusters with eccentricity. H3 cells were larger and had a larger number of dendritic clusters than H1 cells. Owl-monkey H1 cells had larger dendritic fields than capuchin monkey H1 cells at all quadrants in the central and midperipheral retinal regions, but the difference disappeared in the far periphery. Owl-monkey and capuchin monkey H1 cells had about the same number of dendritic clusters across eccentricity. As owl-monkey H1 cells were larger than capuchin monkey H1 cells, the equal number of clusters in these two primates was due to the fact that they were more spaced in the owl-monkey cells. H1 intercluster distance closely matched intercone spacing for both the owl-monkey and capuchin monkey retinas. On the other hand, H3 intercluster distance was larger than intercone spacing in the retina of both primates. Owl-monkey H1 axon terminals had 2-3 times more knobs than capuchin monkey H1 axon terminals in spite of having about the same size and, consequently, knob density was 2-3 times higher for owl-monkey than capuchin monkey H1 axon terminals across all eccentricities. The differences observed between owl-monkey and capuchin monkey horizontal cells, regarding the morphology of their dendritic trees and axon terminals, may be related to the differences found in the cone-to-rod ratio in the retina of these two primates. They seem to represent retinal specializations to the nocturnal and diurnal life styles of the owl-monkey and capuchin monkey, respectively.
对夜行动物枭猴（Aotus）视网膜中的水平细胞形态进行了研究，并将其与昼行性近亲卷尾猴（Cebus）的水平细胞形态进行了比较。细胞最初用碘化丙啶（DiI）标记，随后使用二氨基联苯胺（DAB）作为显色剂将染色光转化为稳定的沉淀物。在不同离心率下测量细胞体、树突野、轴突终末的大小、树突簇的数量、簇间间距和视锥细胞间间距。识别出了两种不同形态类型的水平细胞，它们类似于在昼行性猴子中描述的H1和H3细胞。标记了少数可能对应于昼行性猴子H2细胞的第三类细胞的例子。H1和H3细胞的大小均随着离心率增加而增大，且树突簇数量也增多。H3细胞比H1细胞更大，树突簇数量更多。在视网膜中央和中周边区域的所有象限中，枭猴的H1细胞树突野比卷尾猴的H1细胞树突野更大，但在远周边区域差异消失。枭猴和卷尾猴的H1细胞在不同离心率下树突簇数量大致相同。由于枭猴的H1细胞比卷尾猴的H1细胞更大，这两种灵长类动物中数量相等的树突簇是因为它们在枭猴细胞中分布得更分散。对于枭猴和卷尾猴的视网膜，H1簇间距离与视锥细胞间间距紧密匹配。另一方面，在两种灵长类动物的视网膜中，H3簇间距离均大于视锥细胞间间距。尽管枭猴H1轴突终末与卷尾猴H1轴突终末大小大致相同，但枭猴H1轴突终末的结节数量是卷尾猴H1轴突终末的2 - 3倍，因此在所有离心率下，枭猴H1轴突终末的结节密度比卷尾猴H1轴突终末高2 - 3倍。在枭猴和卷尾猴水平细胞之间观察到的关于其树突树和轴突终末形态的差异，可能与这两种灵长类动物视网膜中视锥细胞与视杆细胞比例的差异有关。它们似乎分别代表了枭猴和卷尾猴对夜行性和昼行性生活方式的视网膜特化。
