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. Author manuscript; available in PMC: 2008 Nov 25.
Published in final edited form as: Dev Dyn. 2008 May;237(5):1359–1372. doi: 10.1002/dvdy.21536

Figure 2. Residual ventral cell-fate specification in the Shh-/- midbrain.

Figure 2

Columns 1, 2: embryos shown in sagittal view with rostral to the right. Columns 3, 4: Midbrain cross-sections with dorsal to the top. Arrowheads in column 2 delineate the midbrain from the hindbrain. The midbrain-hindbrain transition in Shh-/- mouse in this and subsequent figures was determined by the expression of Wnt1, Otx2 and Gbx2, the changed shape of the ventricle, and the presence of the physical constriction delineating midbrain from hindbrain. A-D. Ventrally located Isl1+ OMC neurons present in the controls (arrowhead, A, C) are absent from the Shh-/- midbrain (B, D). Dorsal Isl1+ trigeminal sensory neurons (arrows A, C) are expanded ventrally and rostrally (arrows, B, D). Broken line in B marks the plain of section shown in D. E-H. E10.5 embryos showing that Phox2a+ expression, present exclusively in the OMC (E, G), is completely missing in the Shh-/- midbrain (F, H). The cross-section in H demonstrates that the faint labeling seen in F (*) is outside the midbrain. I-L. E10.5 embryos showing that Pax6+ cells (arrow in I, K) are missing from the Shh-/- midbrain (J, L). Arrow in J marks the residual diencephalon in the Shh-/- embryos. M-P. Some Evx1+ neurons are present in the E12.5 Shh-/- midbrain (N, P). Control emrbyos are shown in M, O. Abbreviations: FB; forebrain; HB: hindbrain; MB: midbrain; MHB: midbrain-hindbrain boundary; OMC: oculomotor complex.