Figure 3. Treatment of cultured skin explants with cyclopamine results in a loss of shh expression. Explants from stage 31 embryos were cultured for 3 days in the presence of HPCD (left) or of HPCD containing 5µg of cyclopamine (right) and the expression of shh was detected by in Situ hybridization. The control explants show expression of shh in the tips of the short buds. In contrast, no localized expression of shh was detected in the cyclopamine-treated explants.