What determines which subpopulation of motor neuron pools a differentiating spinal motor neuron will belong to?
O Cells in different motor neuron pools express different levels of Isl-1 and Isl-2.
O Cells at different levels of the spinal cord express unique combinations of Hox genes.
O Cells at different levels of the spinal cord express varying levels of Sonic hedgehog.
O Cells in different motor neuron pools receive different factors from the tissue they innervate.