1. Department of Neurosurgery; Wroclaw University Hospital; Wroclaw; Poland
2. Laboratory of Electron Microscopy Studies, Faculty of Biology and Animal Science; University of Environmental and Life Sciences; Wroclaw; Poland
3. Department of Biomaterials, Faculty of Materials Science and Ceramic; AGH University of Science and Technology; Krakow,; Poland
4. Department of Neurosurgery; Faculty of Postgraduate Medical Training; Wroclaw Medical University; Wroclaw; Poland