Fig. 6. Brightfield photomicrographs of Shh and Pax3 expression in wild-type and transgenic neural tubes. 35S-in situ hybridization for Shh (A,C) and Pax3 (B,D) at E12.5. (A) Shh is expressed in the floor plate (fp) and notocord (nc) in the wild-type embryo. (C) In the transgenic embryos a single notocord is visible and each ectopic neural tubes (arrowheads) has a floor plate. (B,D) Pax-3 mRNA is normally expressed in the dorsal neural tube in wild-type (B) and transgenic (D) embryos. Ventrally located neural tubes (arrowheads) show no Pax3 signal in the transgenic conceptuses. Bar: 50 µm.