Stocum D L, Thoms S D
J Exp Zool. 1984 Nov;232(2):207-15. doi: 10.1002/jez.1402320208.
The effects of retinoic acid on the regeneration of double anterior lower arms in the adult newt, Notophthalmus viridescens, were investigated. Normally, double anterior lower arms regenerate a hypomorphic, symmetrical pattern of structures, which are distally complete; and double anterior upper arms regenerate a hypomorphic, symmetrical but distally incomplete pattern of structures. In limbs with a normal anteroposterior axis, the major effect of retinoic acid is to alter the proximodistal (PD) positional value of cells local at the amputation level to a much more proximal value, thereby creating duplications in the regenerate of structures proximal to the amputation plane (Thoms and Stocum, '84). Therefore, we predicted that double anterior lower arms treated with retinoic acid would regenerate like double anterior upper arms. However, in a substantial number of cases, each half of these double anterior lower arms regenerated a limb that was complete in the anteroposterior (AP) axis, with asymmetry corresponding to the half of origin. In addition, these regenerates were serially duplicated in the PD axis. These results indicate that retinoic acid can posteriorize the positional value of midline cells, leading to restoration of normal AP pattern, when the set of posterior-half positional values is removed from the cross section of the limb.
研究了视黄酸对成年美西螈（绿红东美螈，Notophthalmus viridescens）双侧前下臂再生的影响。正常情况下，双侧前下臂再生出一种结构发育不全、对称且远端完整的模式；而双侧前上臂再生出一种结构发育不全、对称但远端不完整的模式。在具有正常前后轴的肢体中，视黄酸的主要作用是将截肢水平处局部细胞的近远侧（PD）位置值改变为更接近近端的值，从而在截肢平面近端的再生结构中产生重复（汤姆森和斯托库姆，1984年）。因此，我们预测用视黄酸处理的双侧前下臂会像双侧前上臂一样再生。然而，在大量情况下，这些双侧前下臂的每一半都再生出一个在前后（AP）轴上完整的肢体，其不对称性与起源的一半相对应。此外，这些再生肢体在PD轴上呈串联重复。这些结果表明，当从肢体横切面中去除后半部分位置值集时，视黄酸可使中线细胞的位置值向后化，从而恢复正常的AP模式。
