Fig. 4
From: Flight feather development: its early specialization during embryogenesis
Shh expression detected by section in situ hybridization in the FFF region. Cross sections around the bottom region of feather buds in the FFF region at E13 (a, d and g), E14 (b, e and h) and E15 (c, f and i) at shallow (a–c), middle (d–f) and deep (g–i) levels under the skin. Asterisk in i indicates an irregular pattern of shh expression that represents the position of the prospective rachis. j. an illustrated image showing positional relation of sections (a–i) along depth direction. Scale bars: 100 μm