Figure 1. Treatment of cultured skin explants with cyclopamine inhibits feather bud formation. Skin explants from stage 28 embryos were cultured for 3 days in the presence of HPCD (top) orHPCD containing 5µg of cyclopamine (bottom). In the control, the explant develops to the short bud stage. In contrast, feather bud formation is inhibited in the cyclopamine-treated explants.