In vivo labeling of cells in the ependyma/subventricular zone of adult rats

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 μL 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 DiI 24-48 h after injection (10 μL of 2 g/L) into the lateral ventricle.