Fig. 3
From: Flight feather development: its early specialization during embryogenesis
Whole-mount observations of shh expression in the abdominal and FFF regions. a–c, g–i shh expression in the abdominal tract by whole-mount in situ hybridization from E10 (HHstage 36) to E16 (HHstage 42). d–f, j–l shh expression in the FFF region. Arrowheads in (d–f), (j), (k) indicate feather buds in the FFF region: note that in j and k, feather buds in the FFF region have little shh expression