Berson D M, Pu M, Famiglietti E V
Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA.
J Comp Neurol. 1998 Sep 21;399(2):269-88. doi: 10.1002/(sici)1096-9861(19980921)399:2<269::aid-cne9>3.0.co;2-z.
We define a new morphological type of ganglion cell in cat retina by using intracellular staining in vitro. The zeta cell has a small soma, slender axon, and compact, tufted, unistratified dendritic arbor. Dendritic fields were intermediate in size among cat ganglion cells, typically twice the diameter of beta cell fields. They were smallest in the nasal visual streak (<280 microm diameter), especially near the area centralis (60-150 microm diameter), and largest in the nonstreak periphery (maximum diameter 570 microm). Fields sizes were symmetric about the nasotemporal raphe except near the visual streak, where nasal fields were smaller than temporal ones. Zeta-cell dendrites ramified near the boundary between sublaminae a and b (OFF and ON sublayers) of the inner plexiform layer, occupying the narrow gap separating the dendrites of ON and OFF alpha cells. There was no evidence for separate ON and OFF types of zeta cell. Retrograde labeling studies revealed that both nasally and temporally located zeta cells project to the contralateral superior colliculus, whereas few project to the ipsilateral colliculus or to any subdivision of the dorsal lateral geniculate nucleus. The zeta cell's morphology and projection patterns suggest that it corresponds to the ON-OFF phasic W-cell (also known as the local edge detector) of physiological studies. Zeta cells have particularly small dendritic fields in the visual streak, presumably because they are disproportionately represented in the streak in comparison with other ganglion cell types. These conditions are consistent with optimal spatial resolution along the retinal projection of the visual horizon rather than principally at the center of gaze. Strong commonalities with similar ganglion cell types in ferret, rabbit, and monkey suggest that "zeta-like" cells may be a universal feature of the mammalian retina.
我们通过体外细胞内染色法定义了猫视网膜中一种新的神经节细胞形态类型。ζ细胞具有小的胞体、细长的轴突以及紧密、丛状、单分层的树突分支。在猫的神经节细胞中，ζ细胞的树突野大小处于中等水平，通常是β细胞树突野直径的两倍。它们在鼻侧视条纹中最小（直径<280微米），尤其是在中央凹附近（直径60 - 150微米），而在非条纹周边最大（最大直径570微米）。除了视条纹附近，树突野大小关于鼻颞中缝对称，在视条纹附近，鼻侧树突野比颞侧树突野小。ζ细胞的树突在内网状层的a和b亚层（OFF和ON子层）之间的边界附近分支，占据了分隔ON和OFFα细胞树突的狭窄间隙。没有证据表明存在单独的ON型和OFF型ζ细胞。逆行标记研究显示，位于鼻侧和颞侧的ζ细胞都投射到对侧上丘，而很少投射到同侧上丘或背外侧膝状体核的任何亚区。ζ细胞的形态和投射模式表明它相当于生理学研究中的ON - OFF相性W细胞（也称为局部边缘检测器）。ζ细胞在视条纹中的树突野特别小，推测是因为与其他神经节细胞类型相比，它们在视条纹中的占比不成比例。这些情况与沿视觉地平线的视网膜投射的最佳空间分辨率一致，而不是主要在注视中心。与雪貂、兔子和猴子中类似神经节细胞类型的强烈共性表明，“类ζ”细胞可能是哺乳动物视网膜的一个普遍特征。
