| Cholinergic neurons are concerned with human activities, studying and memory, also the target cells of several degenerative diseases in clinical medicine. Therefore, the generation of cholinergic neurons is the basic work of understanding the function of human brain and exploring the approach of treating those diseases. The dorsal telencephalon is the anlage of pallium. The pallium is classically subdivided into the medial pallium (MP), dorsal pallium (DP), and lateral pallium (LP), giving rise to the archicortex (hippocampus), neocortex, and paleocortex, respectively. The ventricular zone (VZ) and the subventricular zone (SVZ) of dorsal telencephalon are the cradles of the neocortex pyramidal neurons. Generally, most neocortex pyramidal neurons are GABA-containing neurons. And yet, there are a large number of cholinergic neurons in the layers III and V of neocortex. In the generation days of neocortex pyramidal neurons, the 98%cells in ventricular zone is Radial Glia. Radial Glia is a special cell type, which has double characters belong to glial cells and neural stem cells. Firstly, their somas located in the ventricular zone, and their process became the falseworks directed the migration of blastneurons. Besides these characteristics, Radial Glia also exhibit other hallmarks of glial cells, such as a mass of glycogen granules in the cytoplasm, the process contacted close to blood vessels, the cell junctions between Radial Glia cells and the expression of Vimentin and RC2, which both are the special markers of immature glial cells. The latter behaves that Radial Glia can generate blastneurons through symmetry mitosis and asymmetry mitosis in the VZ and the SVZ, and express nestin, which is the special marker of neuroepithelial cells. Confirmed by experiment, Radial Glia can generate virtually all cortical projection neurons but not the interneurons originating in the ventral telencephalon. Through the observation in morphology on dorsal telencephalon Radial Glia to explore the relationship between Radial Glia and cholinergic neurons, our experiment wants to look for the experiment proof to prove that the Radial Glia, located in the dorsal telencephalon, can generate the neocortex cholinergic neurons.Our experiment observed the morphological characteristics of Radial Glia generated pyramidal neurons in cerebral cortex of E12-18 rats, the cell division and its relationship with cholinergic neurons by using the methods of Immunohistochemistry and Electron Microscopy. First of all, we immuno-labeled the Radial Glia with the monoclonal antibody Vimentin in the sections of coronal telencephalon (Vimentin is the special marker of Radial Glia). The result showed that the bodies of Vimentin positive cells located in the ventricular zone, a long process extending to the pial surface, a lot of cell division postures in the ventricular zone. The quantities of cell division postures and Vimentin positive cells decreased gradually, along with the increasing of embryo age. For observing the cell migration after mitosis, BrdU was injected in cavitas peritonealis of E14 and E16 rats during consecutive two days before the animals being killed. We found that the cells marked with BrdU transfered to the outer edge of cortex plate. In the visual field of Electron Microscopy, we found that in addition to the neural features of precursor cell, such as postures of symmetry mitosis and asymmetry mitosis, Radial Glia even have the characters of glial cells, for example, tight junction with micro-vasculosus, junction complexes between Radial Glia cells or Radial Glia cells with non-radial glia cells, the neural progenitor cells in the outskirt of Radial Glia arranging to columns by the long process of Radial Glia, etc. For the sake of testing whether the radial Glia in dorsal telencephalon can generate cortex cholinergic neurons, we double immuno-labeled Radial Glia with Vimentin and choline acetyltransferase (ChAT, the special marker of cholinergic neurons). The result indicated that there was a ChAT positiv... |
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