The Neural Stem Cell and Neuroepithelial Tumor Isolation and Upkeep Core will coordinate maintenance of neural stem cells and neoplastic cell lines. It will also coordinate distribution of these cells to various individual projects. This core will maintain a library of frozen neurosurgical specimens for use in the various projects. Fetal, post- natal, and adult stem cells will be harvested in the core. The core will use cell culture techniques to provide these services. Because each of the projects requires the use of these cells, the core will ensure quality control of the primary research substrates of the program project. Quality control will be ensured by 1) standard cell culture techniques maintaining low passage number, 2) immunohistochemical staining, 3) RT-PCR banding patterns, and 4) timed pregnancies of the animals from which the fetal cells are harvested.