The origin of flaps was frontonasal flap in 58 cases, bilobed flap in 67 cases, reforming rhomboid flap in 152 cases, nasolabial flap in 118 cses, forehead falp in 33 cases.

瓣来源于瓣58，双叶瓣67，改良菱形瓣152，唇沟瓣118，正中瓣33。

Bilateral oal thickenings of the surface ectoderm, called nasal placodes, then deelop on each side of the inferior part of the frontonasal prominence.

外面呈双边卵圆形增厚形成板，然后发展成为隆起的下半部分。