Brunso-Bechtold J K, Vinsant S L
Department of Neurobiology and Anatomy, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103.
J Comp Neurol. 1990 Nov 22;301(4):585-603. doi: 10.1002/cne.903010408.
In normal development, cell layers in the dorsal lateral geniculate nucleus (dLGN) segregate from a relatively homogeneous cell group. If all retinal input is removed prior to this segregation, the layers fail to form. In the present study, we used ultrastructural and morphometric analyses to study dLGN development in the tree shrew following neonatal removal of retinal input. The goal of the present study was to determine whether there are differences between normal animals and enucleates in the development of dLGN cells and their interrelationships with each other and/or with the surrounding glia, which might explain the failure of cellular lamination in enucleated animals. The results indicate that although the development in enucleated animals may take place somewhat more slowly, by P90 cell size and density are not significantly different from normal. These results, coupled with the observation that the dLGN in enucleates is smaller than in normals, suggest that the removal of retinal input results in dLGN cell loss. At both the light and electron microscopic level, cells in the developing normal dLGN are arranged in bands of immediately adjacent cells. In enucleates, dLGN cells are less frequently in immediate contact and are arranged in small groups or clumps which may be separated by degenerating cells. The present data suggest that the presence of retinal input may be necessary to allow dLGN cells to maintain the intercellular relationships necessary for laminar segregation to take place.
在正常发育过程中，背外侧膝状核（dLGN）中的细胞层从相对均匀的细胞群中分离出来。如果在这种分离之前去除所有视网膜输入，这些层就无法形成。在本研究中，我们使用超微结构和形态计量学分析来研究新生树鼩视网膜输入去除后dLGN的发育。本研究的目的是确定正常动物和去眼球动物在dLGN细胞发育及其相互关系以及与周围神经胶质细胞的关系方面是否存在差异，这可能解释去眼球动物细胞分层失败的原因。结果表明，虽然去眼球动物的发育可能会稍微慢一些，但到P90时，细胞大小和密度与正常动物没有显著差异。这些结果，再加上去眼球动物的dLGN比正常动物小的观察结果，表明视网膜输入的去除导致dLGN细胞丢失。在光学和电子显微镜水平上，正常发育的dLGN中的细胞排列成紧邻细胞的条带。在去眼球动物中，dLGN细胞很少直接接触，而是排列成小群或团块，可能被退化的细胞隔开。目前的数据表明，视网膜输入的存在可能是dLGN细胞维持层状分离所需的细胞间关系所必需的。
