Fig. 6.

Loss of Lmx1a/b results in absence of the typical rhombencephalic form with a IVth ventricle covered by a choroid plexus. It also eliminates the midbrain-hindbrain boundary and thus anterior hindbrain/midbrain structures such as oculomotor and trochlear motneurons and the substantia nigra. The cross sections of the alar plate show the partially overlapping expression of different factors in the alar plate that regulate development of subpopulations in rhombomere 7. Note that the expression domains of bHLH genes in r1–5 are only partially clarified. Note also that loss of Lmx1a/b eliminates expression of Atoh1 and Wnt1 throughout most of the hindbrain. Modified after (Mishima et al. 2009; Ray and Dymecki 2009)