Application of HBC/PBS-soaked beads (a) or HBC/Bmp2-soaked beads at HH21 (b) do not affect digit patterning (n = 8/8 and 10/10, respectively). Wings with four digits following cyclopamine-treatment at HH20 have a 1-2-2-2 digit pattern (c, d - 47%, n = 8/18) or a 1-2-2-3 pattern (c, e - 53%, n = 10/18). Application of Bmp2-soaked beads 2 hr later into the right-hand wings buds of the same cyclopamine-treated embryos results in a 1-2-3 digit pattern (c, f - 94%, n = 17/18) or a 1-2-2 pattern (c, 6%, n = 1/18). 53% of cyclopamine-treated wings have a posterior digit 3, but 94% of cyclopamine/Bmp2-treated wings have a posterior digit 3 (g, χ2 test p =< 0.0001). Scale bars: 1 mm.