Figure 6.

Wnt signaling is not required for the maintenance of Shh expression in the ZLI. A, Schematic representation of the neural tube explants in which Dkk-1 or PBS-soaked beads were inserted at the left or right side, respectively. B, Shh expression in HH21 cultured explants 24 h after culture. PBS-soaked beads (black asterisk) or Dkk-1-soaked beads (red asterisk) were inserted into the dorsal region of the ZLI of chick embryos at stage HH21. No modification of Shh expression was observed after blocking Wnt signaling in the experimental side. D, Diencephalon; M, mesencephalon; T, telencephalon; Rh, rhombencephalon.