Hurle J M, Colvee E
J Embryol Exp Morphol. 1982 Jun;69:251-63.
The formation of the free digits of the chick is accompanied by conspicuous surface changes of the interdigital ectoderm. These changes were much less pronounced or absent in the duck. As early as the interdigital grooves were detected in the chick, the morphological features of the ectodermal cells changed from a polygonal shape and flattened appearance to a rounded shape and bulging appearance. These changes were not present in the webbed foot of the duck. On the other hand the development of the interdigital commissures was accompanied by the formation of ectodermal ridges consisting of an accumulation of rounded cells which were in some cases in course of detachment to the amniotic cavity. These ridges were very prominent in all the interdigital commissures of the chick. In the duck they were less pronounced and were only present in the first and third commissure. From these results it is suggested that in addition to the well-known interdigital mesenchymal necrotic process (INZ) the ectodermal tissue of the interdigits might also be actively involved in the formation of free digits.
鸡游离趾的形成伴随着趾间外胚层明显的表面变化。这些变化在鸭中不太明显或不存在。早在鸡的趾间沟被检测到时，外胚层细胞的形态特征就从多边形和平坦外观变为圆形和凸起外观。这些变化在鸭的蹼足中不存在。另一方面，趾间连合的发育伴随着外胚层嵴的形成，外胚层嵴由圆形细胞的聚集组成，在某些情况下这些细胞正脱离进入羊膜腔。这些嵴在鸡的所有趾间连合中都非常突出。在鸭中，它们不太明显，仅存在于第一和第三连合处。从这些结果表明，除了众所周知的趾间间充质坏死过程（INZ）外，趾间的外胚层组织可能也积极参与游离趾的形成。
