Expression of Drg11 in the PrV, SpVi, and SpVc. Drg11 expression detected by X-gal staining (A,B) and in situ hybridization (C-F) in transverse sections through the hindbrain. A, At E10.5, Drg11 is expressed in presumptive PrV cells that begin to emerge from the ventricular zone of the ventral hindbrain (arrow). B, At E11.5, Drg11 expression increases as more PrV cells emerge from the ventricular zone (arrow). C, At E12.5, Drg11 expression is concentrated in the presumptive PrV region. D, At E15.5, Drg11 expression encompasses PrV. E, No Drg11 expression is detected in the SpVi. F, Drg11 is expressed in laminae I-II but not in III-IV of the SpVc. Mo, Motor trigeminal nucleus, t: spinal trigeminal tract. Scale bars, 100 μm.