Abstract: The present invention is directed to a method of isolating an enriched or purified population of motor neurons from a population of embryonic stem cells. This method involves providing a population of embryonic stem cells and selecting a promoter or enhancer which functions only in the motor neurons selected. A nucleic acid molecule encoding a marker protein under control of the promoter or enhancer is introduced into the induced population of embryonic stem cells. The motor neurons are allowed to express the marker protein and, the cells expressed in the marker protein are separated from the population of embryonic stem cells. The population of embryonic stem cells can be induced to produce a mixed population of cells comprising motor neurons before or after a nucleic acid molecule encoding the marker protein under control of the promoter enhancer is introduced into the population of embryonic stem cells. As a result, an enriched or purified population of motor neurons is isolated.