Schmidt M, Lehnert G, Baker R G, Hoffmann K P
Allgemeine Zoologie und Neurobiologie, Ruhr-Universität, Bochum, Germany.
J Comp Neurol. 1996 Jun 10;369(4):520-32. doi: 10.1002/(SICI)1096-9861(19960610)369:4<520::AID-CNE3>3.0.CO;2-6.
The distribution and dendritic morphology of neurons in the cat pretectal nuclear complex were analyzed with respect to their projection to the ipsilateral dorsal lateral geniculate nucleus (LGNd) and the ipsilateral inferior olive (IO). Single and double retrograde tracing techniques were combined with intracellular injections of either horseradish peroxidase into electrophysiologically identified pretectal neurons or Lucifer Yellow into retrogradely labeled somata. Pretectal cells afferent to the LGNd were located in the nucleus of the optic tract (NOT), adjacent dorsal terminal nucleus of the accessory optic system (DTN), and posterior pretectal nucleus (NPP). Cells projecting to the IO were also distributed throughout the NOT-DTN and dorsal part of the NPP. Separate tracer injections (fluorogold and horseradish peroxidase [HRP] or granular blue) into the LGNd and the IO showed considerable overlap of labeled neurons in the NOT and dorsal NPP. Double-labeled neurons, however, were not observed after double tracer injections into LGNd and IO. Partial topographical segregation of the two populations was observed along the dorsoventral axis because LGNd-projecting neurons exhibited maximum density ventral to that of IO neurons. Pretectal cells to the LGNd had cell body diameters between 16 and 48 microns. Somatic shapes varied between fusiform and multipolar with considerable overlap between these two morphological appearances. Neurons projecting to the IO exhibited similar cell body sizes and their morphology also varied from fusiform to multipolar. Quantitative analysis of dendritic field size and orientation, number and order of dendritic arborizations, and symmetry of the dendritic tree revealed no statistically significant difference between the two neuronal populations. Hence, neurons of the two populations cannot be unequivocally identified just from the dendritic morphology. By contrast, dendritic morphology was correlated with the topographical location of either cell type within the pretectal nuclei rather than projection. Thus, the morphological appearance of neurons located dorsally predominantly was fusiform while neurons located ventrally mostly were multipolar.
关于猫顶盖前核复合体中神经元向同侧背外侧膝状体核（LGNd）和同侧下橄榄核（IO）的投射，分析了这些神经元的分布和树突形态。将单逆行示踪技术和双逆行示踪技术与向经电生理鉴定的顶盖前神经元内注射辣根过氧化物酶或向逆行标记的胞体内注射路西法黄相结合。投射到LGNd的顶盖前细胞位于视束核（NOT）、副视系统相邻背侧终末核（DTN）和顶盖前核后部（NPP）。投射到IO的细胞也分布于整个NOT-DTN和NPP的背侧部分。分别向LGNd和IO注射示踪剂（荧光金和辣根过氧化物酶[HRP]或颗粒蓝）显示，NOT和NPP背侧的标记神经元有相当大的重叠。然而，向LGNd和IO双注射示踪剂后未观察到双标记神经元。沿背腹轴观察到这两类神经元有部分拓扑分离，因为投射到LGNd的神经元在腹侧表现出最大密度，其密度高于投射到IO的神经元。投射到LGNd的顶盖前细胞的胞体直径在16至48微米之间。胞体形状在梭形和多极形之间变化，这两种形态外观之间有相当大的重叠。投射到IO的神经元表现出相似的胞体大小，其形态也从梭形到多极形变化。对树突野大小和方向、树突分支的数量和顺序以及树突树的对称性进行定量分析，结果显示这两类神经元之间没有统计学上的显著差异。因此，不能仅从树突形态明确区分这两类神经元。相比之下，树突形态与顶盖前核内这两种细胞类型的拓扑位置相关，而非与投射相关。因此，主要位于背侧的神经元形态主要为梭形，而位于腹侧的神经元大多为多极形。
