Flight feather development: its early specialization during embryogenesis

Development of remex-type flight feathers after hatching. a A flight feather in the adult chicken. b Natal down feather in the abdominal tract at 1 dph. An uprooted abdominal natal down feather is shown on the right side. c Ventral view of the FFF region at 1 dph. Some rows of feathers in the ventral surface of the wing are trimmed. Staples indicate the FFF region. An magnified photograph is shown on the right side. d–f A feather uprooted from the FFF region at 1 dph (d), 5 dph (e), and 7 dph (f). Note that in e, a distal downy part is connected with a proximal bilateral part that starts opening (white arrow). Scale bars: 1 c