Nestin is an intermediate filament protein first described in early embryonic neuroepithelial stem cells. Although not found in most cells of the mature CNS, nestin is the predominant marker used to detect the small population of undifferentiated cells. The presence of nestin identifies stem, progenitor and some tumor cells in the CNS, and also labels areas of reactive gliosis in the CNS. Available methods to detect nestin use antibodies generated against rat nestin protein. Since rat and human nestin have only about fifty percent sequence homology, these antibodies may not be optimal for detecting nestin in human cells. NIH scientists used a novel human nestin immunogen to generate polyclonal and monoclonal antibodies that bind with high affinity and specificity to human nestin. The immunogen was expressed from a 450 base-pair segment of human nestin mRNA, which has 11 nucleotide differences from previously published human nestin. These antibodies increase the specificity to accurately detect human nestin in all stages of brain development and will increase our understanding of glial differentiation. In addition, this technology may be useful for detecting glioblastomas or other early stage neuroectodermal tumors and for following transplanted stem cells.