Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Japan.
Science. 2011 Feb 11;331(6018):753-7. doi: 10.1126/science.1198229.
The identities of the digits of the avian forelimb are disputed. Whereas paleontological findings support the position that the digits correspond to digits one, two, and three, embryological evidence points to digit two, three, and four identities. By using transplantation and cell-labeling experiments, we found that the posteriormost digit in the wing does not correspond to digit four in the hindlimb; its progenitor segregates early from the zone of polarizing activity, placing it in the domain of digit three specification. We suggest that an avian-specific shift uncouples the digit anlagen from the molecular mechanisms that pattern them, resulting in the imposition of digit one, two, and three identities on the second, third, and fourth anlagens.
鸟类前肢指节的身份存在争议。虽然古生物学发现支持指节对应于数字 1、2 和 3 的观点，但胚胎学证据指向数字 2、3 和 4 的身份。通过使用移植和细胞标记实验，我们发现翅膀中最靠后的手指与后肢的第四根手指不对应；它的祖细胞很早就从极化活性区分离出来，将其置于第三根手指的指定区域。我们认为，鸟类特有的转变将指节原基与塑造它们的分子机制分离，导致第二、第三和第四根原基被赋予第一、第二和第三根指节的身份。
