Kenigfest N, Martínez-Marcos A, Belekhova M, Font C, Lanuza E, Desfilis E, Martínez-García F
Laboratory of Evolution of Neuronal Interactions, Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
Brain Behav Evol. 1997;50(6):313-34. doi: 10.1159/000113344.
The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells, is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.
这项工作的目的是描绘蜥蜴背侧丘脑的视网膜接收细胞群，并研究一些差异连接，以帮助理解四足动物视觉系统的进化。将示踪和免疫组织化学技术应用于西班牙壁蜥视网膜接收的背侧丘脑。西班牙壁蜥的视网膜投射到背侧丘脑的四个区域：椭圆核（Ov）、间膝叶（IGL）、背外侧膝状核（GLD）和背外侧前核（DLA）。椭圆核呈现出清晰的细胞板/神经毡组织，并投射到腹侧丘脑。因此，它似乎属于腹侧丘脑而非背侧丘脑。IGL包含对GABA和/或NPY免疫组织化学有反应的大细胞。它与视交叉上/视交叉后下丘脑相互连接，并投射到对侧丘脑和同侧顶盖。尾侧DLA缺乏GABA样和NPY样免疫反应性细胞，虽然有少数细的视网膜纤维到达该区域，但DLA细胞的远端树突进入GLD，提示有重要的视网膜输入。DLA投射到内侧和背侧端脑皮质。GLD是主要的视网膜接收丘脑结构，投射到端脑。它呈现出粗略的分层组织，其中细胞板神经元投射到同侧脑皮质增厚处，但它不接受来自视觉端脑的下行投射，因此与其他羊膜脊椎动物的GLD不同。根据目前的知识，这些结果表明在所有研究的四足动物中都存在IGL同源物，而Ov似乎仅限于双孔类脊椎动物。此外，我们的数据表明，向端脑的单峰视觉投射（起源于GLD）最早是在爬行动物中通过从边缘（多峰）丘脑 - 端脑通路分离而出现的。
