glioblast glioblast a glioblast is a type of cell derived from neuroectoderm and with the ability to differentiate into several different types of neuroglia. it comes from a precursor (spongioblast). however, the latter may also differentiate into an ependymoblast. glioblasts differentiate into astrocytes and oligodendrocytes. its tumor is called a glioblastoma, and is the most common type of central nervous system malignancy.