Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea.
Cell Tissue Res. 2010 Feb;339(2):311-20. doi: 10.1007/s00441-009-0895-6. Epub 2009 Nov 25.
In the mammalian retina, information concerning various aspects of an image is transferred in parallel, and cone bipolar cells are thought to play a major role in this parallel processing. We have examined the synaptic connections of calbindin-immunoreactive (IR) ON cone bipolar cells in the inner plexiform layer (IPL) of rabbit retina and have compared these synaptic connections with those that we have previously described for neurokinin 1 (NK1) receptor-IR cone bipolar cells. A total of 325 synapses made by calbindin-IR bipolar axon terminals have been identified in sublamina b of the IPL. The axons of calbindin-IR bipolar cells receive synaptic inputs from amacrine cells through conventional synapses and are coupled to putative AII amacrine cells via gap junctions. The major output from calbindin-IR bipolar cells is to amacrine cell processes. These data resemble our findings for NK1 receptor-IR bipolar cells. However, the incidences of output synapses to ganglion cell dendrites of calbindin-IR bipolar cells are higher compared with the NK1-receptor-IR bipolar cells. On the basis of stratification level and synaptic connections, calbindin-IR ON cone bipolar cells might thus play an important role in the processing of various visual aspects, such as contrast, orientation, and approach sensing, and in transferring rod signals to the ON cone pathway.
在哺乳动物的视网膜中，与图像的各个方面有关的信息是平行传递的，而锥形双极细胞被认为在这种平行处理中起着主要作用。我们已经检查了兔视网膜内丛状层（IPL）中钙结合蛋白免疫反应（IR）的 ON 锥形双极细胞的突触连接，并将这些突触连接与我们之前描述的神经激肽 1（NK1）受体-IR 锥形双极细胞的突触连接进行了比较。在 IPL 的子层 b 中已经确定了 325 个由钙结合蛋白 IR 双极轴突末端形成的突触。钙结合蛋白 IR 双极细胞的轴突通过常规突触从无长突细胞接收突触输入，并通过缝隙连接与假定的 AII 无长突细胞偶联。钙结合蛋白 IR 双极细胞的主要输出是向无长突细胞过程。这些数据与我们对 NK1 受体-IR 双极细胞的发现相似。然而，与 NK1 受体-IR 双极细胞相比，钙结合蛋白 IR 双极细胞向神经节细胞树突输出突触的发生率更高。基于分层水平和突触连接，钙结合蛋白 IR 的 ON 锥形双极细胞可能在处理各种视觉方面（如对比度、方向和接近感）以及将杆信号传递到 ON 锥形途径方面发挥重要作用。
