Cadi R, Dhouailly D, Sengel P
Dev Biol. 1983 Dec;100(2):489-95. doi: 10.1016/0012-1606(83)90241-5.
Feet of chicks are normally covered with scales. Injection of retinoic acid into the amniotic cavity of 10-day chick embryos causes the formation of feathers on the foot scales. To elucidate whether retinoic acid affects primarily the epidermis or the dermis, heterotypic dermal-epidermal recombinants of tarsometatarsal skin were tested as to their morphogenetic capacity, when grafted to the chick chorioallantoic membrane. Recombinants involving treated epidermis and untreated dermis formed feathered scales, while the reverse recombinants of untreated epidermis and treated dermis led to the formation of scales only. Likewise the association of treated tarsometatarsal dermis with untreated epidermis from a non-appendage-forming region (the midventral apterium) resulted in the formation of scales only. These results show that retinoic acid affects primarily the epidermis. Further insight into the mechanism of dermal-epidermal interaction was gained by heterotopic recombinations of early (8.5- and 10-day) untreated tarsometatarsal dermis with epidermis from the midventral apterium. These recombinants formed scales, proving that tarsometatarsal dermis is endowed with scale-forming properties as early as 8.5 days of incubation. Finally, it is concluded that retinoic acid acts on the chick foot epidermal cells by temporarily inhibiting their scale placode-forming properties, allowing their latent feather placode-forming properties to be expressed.
小鸡的足部通常覆盖着鳞片。将视黄酸注入10日龄小鸡胚胎的羊膜腔会导致足部鳞片上形成羽毛。为了阐明视黄酸主要影响表皮还是真皮，将跗跖皮肤的异型真皮-表皮重组体移植到小鸡尿囊绒膜上，测试其形态发生能力。涉及处理过的表皮和未处理的真皮的重组体形成了有羽毛的鳞片，而未处理的表皮和处理过的真皮的反向重组体仅导致鳞片的形成。同样，处理过的跗跖真皮与来自非附属物形成区域（腹中部无羽区）的未处理表皮结合，也仅导致鳞片的形成。这些结果表明视黄酸主要影响表皮。通过将早期（8.5天和10天）未处理的跗跖真皮与腹中部无羽区的表皮进行异位重组，进一步深入了解了真皮-表皮相互作用的机制。这些重组体形成了鳞片，证明跗跖真皮早在孵化8.5天时就具有形成鳞片的特性。最后得出结论，视黄酸作用于小鸡足部表皮细胞，通过暂时抑制其鳞片基板形成特性，使其潜在的羽毛基板形成特性得以表达。
