Joo Hannah R, Peterson Beth B, Haun Toni J, Dacey Dennis M
Department of Biological Structure and the National Primate Research Center, University of Washington, Seattle, Washington, USA.
Vis Neurosci. 2011 Jan;28(1):29-37. doi: 10.1017/S0952523810000374. Epub 2010 Dec 15.
Parallel processing of visual information begins at the first synapse in the retina between the photoreceptors and bipolar cells. Ten bipolar cell types have been previously described in the primate retina: one rod and nine cone bipolar types. In this paper, we describe an 11th type of bipolar cell identified in Golgi-stained macaque retinal whole mount and vertical section. Axonal stratification depth, in addition to dendritic and axonal morphology, distinguished the "giant" cell from all previously well-recognized bipolar cell types. The giant bipolar cell had a very large and sparsely branched dendritic tree and a relatively large axonal arbor that costratified with the DB4 bipolar cell near the center of the inner plexiform layer. The sparseness of the giant bipolar's dendritic arbor indicates that, like the blue cone bipolar, it does not contact all the cones in its dendritic field. Giant cells contacting the same cones as midget bipolar cells, which are known to contact single long-wavelength (L) or medium-wavelength (M) cones, demonstrate that the giant cell does not exclusively contact short-wavelength (S) cones and, therefore, is not a variant of the previously described blue cone bipolar. This conclusion is further supported by measurement of the cone contact spacing for the giant bipolar. The giant cell contacts an average of about half the cones in its dendritic field (mean ± S.D. = 52 ± 17.6%; n = 6), with a range of 27-82%. The dendrites from single or neighboring giant cells that converge onto the same cones suggest that the giant cell may selectively target a subset of cones with a highly variable local density, such as the L or M cones.
视觉信息的并行处理始于视网膜中光感受器与双极细胞之间的第一个突触。先前在灵长类动物视网膜中已描述了10种双极细胞类型：1种视杆双极细胞类型和9种视锥双极细胞类型。在本文中，我们描述了在高尔基染色的猕猴视网膜整装片和垂直切片中鉴定出的第11种双极细胞类型。轴突分层深度，以及树突和轴突形态，将这种“巨型”细胞与所有先前已明确识别的双极细胞类型区分开来。巨型双极细胞具有非常大且分支稀疏的树突树，以及相对较大的轴突分支，其与内网状层中心附近的DB4双极细胞共分层。巨型双极细胞树突分支的稀疏性表明，与蓝视锥双极细胞一样，它在其树突野中并不与所有视锥细胞接触。与侏儒双极细胞接触相同视锥细胞的巨型细胞（已知侏儒双极细胞接触单个长波长（L）或中波长（M）视锥细胞）表明，巨型细胞并非仅接触短波长（S）视锥细胞，因此不是先前描述的蓝视锥双极细胞的变体。巨型双极细胞视锥细胞接触间距的测量进一步支持了这一结论。巨型细胞在其树突野中平均接触约一半的视锥细胞（平均值±标准差=52±17.6%；n=6），范围为27-82%。汇聚到相同视锥细胞上的单个或相邻巨型细胞的树突表明，巨型细胞可能选择性地靶向局部密度高度可变的视锥细胞子集，例如L或M视锥细胞。
