Wnt Signaling Is Required for the Generation of dMNs and vMNs in the Hindbrain and Spinal Cord

<div><p>(A) Caudal (C) neural plate tissue explants (black box) were isolated from HH stage 4 embryos. Explants were cultured alone or in the presence of mFrz8CRD-IgG for 28 h and then exposed to Shh-N (15 nM) for an additional 38 h.</p> <p>(B–C) Bars represent mean ± s.e.m. number of <i>Tbx20⁺</i>/Isl⁺, Hb9⁺/Isl⁺, Hb9⁺/Hoxc9⁺, and Isl1⁺ cells, respectively, as percentage of total cell number. Each row represents consecutive sections from a single explant. </p> <p>(B) Stage 4 C explants cultured with Shh-N alone generated <i>Tbx20⁺</i>/Isl⁺ cells in the rostral domain of the explant and Hb9⁺/Isl⁺ cells and Hb9⁺/Hoxc9⁺ cells in the caudal domain of the explant ( <i>n</i> = 18 explants). </p> <p>(C) Explants cultured in the presence of mFrz8CRD-IgG conditioned medium (500 μl/ml culture medium) and Shh-N generated Isl1/2⁺ cells but no <i>Tbx20⁺, </i> Hb9⁺, or Hoxc9⁺ cells ( <i>n</i> = 7 explants). Scale bars represent 100 μm (Isl1/2) and 50 μm (double labels), respectively. </p>