Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
J Comp Neurol. 2012 Nov 1;520(16):3786-802. doi: 10.1002/cne.23168.
Bipolar cells convey luminance, spatial, and color information from photoreceptors to amacrine and ganglion cells. We studied the photoreceptor connectivity of 321 bipolar cells in the adult zebrafish retina. 1,1'-Dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) was inserted into whole-mounted transgenic zebrafish retinas to label bipolar cells. The photoreceptors that connect to these DiI-labeled cells were identified by transgenic fluorescence or their positions relative to the fluorescent cones, as cones are arranged in a highly ordered mosaic: rows of alternating blue- (B) and ultraviolet-sensitive (UV) single cones alternate with rows of red-(R) and green-sensitive (G) double cones. Rod terminals intersperse among cone terminals. As many as 18 connectivity subtypes were observed, 9 of which-G, GBUV, RG, RGB, RGBUV, RGRod, RGBRod, RGBUVRod, and RRod bipolar cells-accounted for 96% of the population. Based on their axon terminal stratification, these bipolar cells could be further subdivided into ON, OFF, and ON-OFF cells. The dendritic spread size, soma depth and size, and photoreceptor connections of the 308 bipolar cells within the nine common connectivity subtypes were determined, and their dendritic tree morphologies and axonal stratification patterns compared. We found that bipolar cells with the same axonal stratification patterns could have heterogeneous photoreceptor connectivity whereas bipolar cells with the same dendritic tree morphology usually had the same photoreceptor connectivity, although their axons might stratify on different levels.
双极细胞将来自光感受器的亮度、空间和颜色信息传递给无长突细胞和神经节细胞。我们研究了成年斑马鱼视网膜中 321 个双极细胞的光感受器连接。1,1'-二辛基-3,3,3',3'-四甲基吲哚羰花青高氯酸盐(DiI)被插入全贴壁转基因斑马鱼视网膜中以标记双极细胞。通过转基因荧光或相对于荧光锥体的位置来鉴定与这些 DiI 标记的细胞相连的光感受器,因为锥体以高度有序的镶嵌排列:交替的蓝色(B)和紫外线敏感(UV)单锥体行与红色(R)和绿色敏感(G)双锥体行交替排列。棒状末梢散布在锥体末梢之间。观察到多达 18 种连接亚型,其中 9 种-即 G、GBUV、RG、RGB、RGBUV、RGRod、RGBRod、RGBUVRod 和 RRod 双极细胞-占总群体的 96%。根据它们的轴突末端分层,这些双极细胞可以进一步细分为 ON、OFF 和 ON-OFF 细胞。在 9 种常见连接亚型内的 308 个双极细胞中,确定了它们的树突扩展大小、体深度和大小以及光感受器连接,并比较了它们的树突形态和轴突分层模式。我们发现,具有相同轴突分层模式的双极细胞可能具有不同的光感受器连接,而具有相同树突形态的双极细胞通常具有相同的光感受器连接,尽管它们的轴突可能在不同的水平分层。