In panel A, the olfactory centre (arrow) in the 12.5 day embryo is positive for the mDuffy. B, C and D show neuronal tracts are positive for mDuffy in the forebrain (B), spinal cord and sensory neurons (C), and limbs (D). Neuronal tracts are positive for KC (E) around the neural tube, but the neuronal tracts in the limb bud are negative for KC (F).