Segregation of On and Off Bipolar Cell Axonal Arbors in the Absence of Retinal Ganglion Cells
Segregation of On and Off Bipolar Cell Axonal Arbors in the Absence of Retinal Ganglion Cells
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DOI：
10.1523/jneurosci.20-01-00306.2000
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发表时间：
2000-01
期刊：
影响因子：
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通讯作者：
Emine Günhan-Agar;D. Kahn;L. Chalupa
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文献类型：
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作者：
Emine Günhan-Agar;D. Kahn;L. Chalupa
对光的开始或消失有选择性反应的视网膜细胞被分为开路和关路。在这里，我们描述了视锥双极细胞的发育，其成熟时的轴突乔木突触到仅限于内丛状层（IPL）的开层和关层的神经节细胞树突上。特别是，我们试图确定这种分离模式的形成是否依赖于神经节细胞的存在。使用针对恢复蛋白的抗体来观察正在发育的双极细胞，恢复蛋白是一种钙结合蛋白，可标记成年大鼠视网膜中的开锥体和离锥体双极细胞。在出生当天 [出生后第 0 天 (P0)]，在双极细胞开始迁移到内核层之前，恢复素阳性细胞在心室区很明显。两个不同的层在 P8 的 IPL 中首先出现，Off 途径比 On 途径成熟得更早。没有迹象表明有旺盛的双极细胞投射。在整个发育过程中，神经节细胞层中还存在少量来源不明的恢复素阳性细胞。为了评估开锥体和离锥体双极细胞投射的形成是否依赖于神经节细胞的存在，通过单侧视神经切片消除了这些目标神经元。这是在出生当天完成的，导致双极细胞轴突支配 IPL 之前 5-6 天神经节细胞完全丧失。在具有视神经切片的视网膜中，存在开锥体和离锥体双极细胞，尽管其密度低于正常密度，并且这些中间神经元的轴突乔木被组织成两个不同的层。这表明神经节细胞对于形成隔离的开和关双极细胞输入并不是必需的。这些结果支持了这样的假设：双极细胞末端乔木的特定向内生长模式可以调节分层视网膜神经节细胞树突的形成。
Retinal cells that respond selectively to light onset or offset are segregated into On and Off pathways. Here, we describe the development of cone bipolar cells whose axonal arbors at maturity synapse onto ganglion cell dendrites confined to On and Off strata of the inner plexiform layer (IPL). In particular, we sought to determine whether the formation of this segregated pattern is dependent on the presence of ganglion cells. Developing bipolar cells were visualized using an antibody against recoverin, the calcium binding protein that labels On and Off cone bipolar cells in the adult rat retina. Recoverin-positive cells were apparent in the ventricular zone on the day of birth [postnatal day 0 (P0)], before bipolar cells begin to migrate to the inner nuclear layer. Two distinct strata were first apparent in the IPL at P8, with the Off pathway maturing earlier than the On pathway. There was no indication of exuberant bipolar cell projections. Throughout development, there were also a small number of recoverin-positive cells of unknown origin in the ganglion cell layer. To assess whether the formation of On and Off cone bipolar cell projections is dependent on the presence of ganglion cells, these target neurons were eliminated by unilateral section of the optic nerve. This was done on the day of birth, resulting in a total loss of ganglion cells 5–6 d before bipolar cell axons innervate the IPL. In retinas with optic nerve sections, On and Off cone bipolar cells were present, albeit at a lower than normal density, and the axonal arbors of these interneurons were organized into two distinct strata. This indicates that ganglion cells are not essential for the formation of segregated On and Off bipolar cell inputs. These results lend support to the hypothesis that specific ingrowth patterns of bipolar cell terminal arbors could regulate the formation of stratified retinal ganglion cell dendrites.