GMCs are the progeny of type I neuroblasts. Kenyon cells are produced from precursors known as neuroblasts. The ependymal cells and astrocytes form glial tubes used by migrating neuroblasts. The number of neuroblasts varies greatly between species. Occasionally, tumors may present neuroepithelium that resemble neuroblasts. Adult SVZ astrocytes also appear to release glutamate to regulate the survival of neuroblasts. Co-expression of proneural genes in brain neuroblasts is transient and varies with the developmental stage. The C cells then produce neuroblasts, or A cells, that will become neurons. CD24 is a sialoglycoprotein expressed at the surface of most B lymphocytes and differentiating neuroblasts. The undifferentiated neuroblasts form chains that migrate and develop into mature neurons. Without reelin, the chain-migrating neuroblasts failed to detach properly. Neuroblasts that form in the lateral ventricle adjacent to the striatum, integrate in the striatum. Nerve fibers emerge from these neuroblasts to form the marginal layer (the white matter). The basal plate neuroblasts will give rise to the motor nuclei. The neuroblasts are the cells that undergo mitotic division and produce neurons.