Miragall F, Kadmon G, Husmann M, Schachner M
Department of Neurobiology, University of Heidelberg, Federal Republic of Germany.
Dev Biol. 1988 Oct;129(2):516-31. doi: 10.1016/0012-1606(88)90397-1.
The expression of the neural cell adhesion molecules N-CAM and L1 was investigated in the olfactory system of the mouse using immunocytochemical and immunochemical techniques. In the olfactory epithelium, globose basal cells and olfactory neurons were stained by the polyclonal N-CAM antibody reacting with all three components of N-CAM (N-CAM total) in their adult and embryonic states. Dark basal cells and supporting cells were not found positive for N-CAM total. The embryonic form of N-CAM (E-N-CAM) was only observed on the majority of globose basal cells, the precursor cells of olfactory neurons, and some neuronal elements, probably immature neurons, since they were localized adjacent to the basal cell layer. Differentiated neurons in the olfactory epithelium did not express E-N-CAM. In contrast to N-CAM total, the 180-kDa component of N-CAM (N-CAM180) and E-N-CAM, L1 was not detectable on cell bodies in the olfactory epithelium. L1 and N-CAM180 were strongly expressed on axons leaving the olfactory epithelium. Olfactory axons were also labeled by antibodies to N-CAM180 and L1 in the lamina propria and the nerve fiber and glomerular layers of the olfactory bulb, but only some axons showed a positive immunoreaction for E-N-CAM. Ensheathing cells in the olfactory nerve were observed to bear some labeling for N-CAM total, L1, and N-CAM180, but not E-N-CAM. In the olfactory bulb, L1 was not present on glial cells. In contrast, N-CAM180 was detectable on some glia and N-CAM total on virtually all glia. Glia in the nerve fiber layer were labeled by E-N-CAM antibody only at the external glial limiting membrane. In the glomerular layer, E-N-CAM expression was particularly pronounced at contacts between olfactory axons and target cells. The presence of E-N-CAM in the adult olfactory epithelium and bulb was confirmed by Western blot analysis. The continued presence of E-N-CAM in adulthood on neuronal precursor cells, a subpopulation of olfactory axons, glial cells at the glia limitans, and contacts between olfactory axons and their target cells indicates the retention of embryonic features in the mammalian olfactory system, which may underlie its remarkable regenerative capacity.
运用免疫细胞化学和免疫化学技术，对小鼠嗅觉系统中神经细胞黏附分子N-CAM和L1的表达进行了研究。在嗅觉上皮中，球状基底细胞和嗅觉神经元被与N-CAM所有三种成分（N-CAM总量）发生反应的多克隆N-CAM抗体染色，这些细胞处于成年和胚胎状态。深色基底细胞和支持细胞未被检测出N-CAM总量呈阳性。N-CAM的胚胎形式（E-N-CAM）仅在大多数球状基底细胞（嗅觉神经元的前体细胞）以及一些神经元成分（可能是未成熟神经元）上观察到，因为它们位于基底细胞层附近。嗅觉上皮中已分化的神经元不表达E-N-CAM。与N-CAM总量不同，N-CAM的180-kDa成分（N-CAM180）和E-N-CAM，在嗅觉上皮的细胞体上未检测到L1。L1和N-CAM180在离开嗅觉上皮的轴突上强烈表达。嗅觉轴突在固有层以及嗅球的神经纤维层和肾小球层也被针对N-CAM180和L1的抗体标记，但只有一些轴突对E-N-CAM呈现阳性免疫反应。观察到嗅神经中的包被细胞对N-CAM总量、L1和N-CAM180有一些标记，但对E-N-CAM没有标记。在嗅球中，神经胶质细胞上不存在L1。相反，在一些神经胶质细胞上可检测到N-CAM180，几乎所有神经胶质细胞上都可检测到N-CAM总量。神经纤维层中的神经胶质细胞仅在外部神经胶质界限膜处被E-N-CAM抗体标记。在肾小球层，E-N-CAM的表达在嗅觉轴突与靶细胞的接触处尤为明显。通过蛋白质印迹分析证实了成年嗅觉上皮和嗅球中存在E-N-CAM。E-N-CAM在成年期持续存在于神经元前体细胞、一部分嗅觉轴突、神经胶质界限处的神经胶质细胞以及嗅觉轴突与其靶细胞之间的接触处，这表明哺乳动物嗅觉系统保留了胚胎特征，这可能是其显著再生能力的基础。
