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Objective: To identify the labeled cells in the ependyma/subventricular zone (SVZ) of normal adult rats by DiI injected into the lateral ventricle., Methods: Fifty male Sprague-Dawley rats were divided randomly into five groups (10 per group). All of the rats were injected with 10 microL of 2 g/L fluorescence dye DiI into the right lateral ventricle. The five groups of rats were sacrificed at 6 h, 12 h, 24 h, 36 h or 48 h after injection respectively. Hoechst 33258 staining was used to identify nuclei and laser confocal microscopy was used to detect the DiI-labeled cells and to measure the thickness of the tissue with DiI fluorescence in the wall of the left lateral ventricle., Results: After injection of the DiI into the right lateral ventricle, DiI- Hoechst 33258 double positive cells were found in the ependymal layer of the left lateral ventricular wall at 24 h and in the SVZ at 48 h as well. The thickness of the tissue with DiI fluorescence in the left ependyma/septal subventricular zone (SVZspt) and ependyma/postnatal equivalent of the ganglionic eminences (SVZge) remained unchanged at 12 h and 24 h after DiI injection. The thickness of the tissue with DiI fluorescence in the left ependyma/SVZge was significantly greater than that in the ependyma/SVZspt at all of the time points (P<0.05)., Conclusion: The ependyma/SVZ cells can be labeled by Dil 24-48 h after injection (10 microL of 2 g/L) into the lateral ventricle.

Objective: To investigate the migration and differentiation of ependymal/subventricular zone cells after focal cerebral ischemia in rats, and reveal the origin of the newly generated neural cells in the peri-infarct region., Methods: Normal adult male Sprague Dawley rats weighing 250-350 g were used in this study. Before middle cerebral artery occlusion (MCAO), 10 microl of 0.2% DiI was injected into the lateral ventricle for prelabeling the ependymal/subventricular zone cells. After ischemia, cumulative BrdU labeling was employed to detect the newly generated cells and double immunofluorescent staining to identify cell differentiation. The labeled cells were observed with laser confocal microscopy., Results: In the non-ischemic control rats, DiI-labeled cells resided in the ependyma/subventricular zone. After focal cerebral ischemia, DiI-labeled cells were found in the corpus callosum, adjacent striatum and cortex, and some DiI/BrdU/glial fibrillary acidic protein (GFAP)-positive cells or DiI/BrdU/ neuronal nuclear antigen (NeuN)-positive cells were observed in the peri-infarct region in the striatum or cortex since day 14 after MCAO., Conclusion: After focal cerebral ischemia, ependymal/subventricular zone cells migrate into the peri-infarct region where they differentiate into neurons and astrocytes. This finding may be important for understanding the source of adult neural stem cells and for developing new therapeutic intervention strategy through enhancing endogenous neurogenesis after brain injury.