The present invention relates generally to a method for the generation of a substantially homogeneous population of undifferentiated cells. More particularly, the present invention relates to the purification of a substantially homogeneous population of stem cells and their progenitor or precursor cells. Even more particularly, the present invention provides a population of neural stem cells (NSCs). The subject invention is particularly directed to NSCs and precursor cells with the capacity to differentiate into cells and cell lineages required for the development, maintenance or repair of the central nervous system in an animal such as a mammal. The present invention is further directed to NSCs and progenitor and/or precursor cells which are capable of proliferation and differentiation into multiple cell lineages, such as but not limited to neurons, oligodendrocytes, glia and astrocytes. The subject invention further contemplates the use of NSCs and/or precursor cells for the repair or regeneration of tissue, such as tissue associated with the central nervous system, in an animal including a mammal. The NSCs of the present invention may be used to identify naturally occurring molecules such as cytokines as well as molecules obtained from natural product screening or screening of chemical libraries which induce proliferation of the NSCs. Such molecules are useful in the development of therapeutics.