Fig. 4. Simultaneous knockdown of Lmx1b.1 and Lmx1b.2 results in a loss of isthmic and cerebellar structures. (A) Specific inhibition of Lmx1b.1 and Lmx1b.2 translation by morpholino oligonucloetides. In vitro translation of Lmx1b.1 (top panel) and Lmx1b.2 (bottom panel) in the absence of oligonuclotide (lane 1) or with addition of: an unrelated oligonucleotide (CON-MO, lane 2), a mismatch oligonucleotide (BN-MO lane 3), or oligonucleotides specific for Lmx1b.1 (B1-MO, lane 4) or Lmx1b.2 (B2-MO, lane 5). (B-E) Lateral views of anterior CNS, with dorsal upwards and anterior leftwards. Microtome sections at 30 hpf (B,C) and whole mounts at 36 hpf (D,E) of embryos injected with B1B2-MO (B,D) or Con-MO (C,E). Red arrowheads indicate the position of the isthmic constriction and white arrowheads indicate the missing isthmic constriction. t, tectum; c, cerebellum; *, missing structures.