Department of Biomedical Sciences, University of Windsor, Windsor, Ontario, Canada.
Dev Dyn. 2021 Jun;250(6):896-901. doi: 10.1002/dvdy.272. Epub 2020 Nov 27.
Unlike axolotls, the urodele Notophthalmus viridescens completes two metamorphoses and emerges from its aquatic environment to mate as a fully terrestrial adult. Larval and adult limb regeneration are commonly treated as roughly equivalent processes and, at least in part, as a recapitulation of embryonic development.
We compared larval limb development to regeneration of both larval and adult forelimbs and found that there are substantial differences in developmental pattern among larvae and adults. The larval pattern of preaxial dominance is absent in adult regenerates: adult regenerates instead develop digits synchronously, and they do so before proximal autopodial elements have formed discrete aggregation zones. By contrast, larval regenerates follow a pattern of sequential digit formation from anterior to posterior, like their embryonic limb buds.
Based upon these morphological clues, we conclude that larval regenerates are unlikely to exhibit features of epimorphic regeneration seen in adults, but are more likely to represent a form of developmental regulation. Furthermore, we confirm that post-metamorphic limb regeneration is not a simple recapitulation of ontology at the morphological level. These distinctions may help to explain and interpret some experiments and observations of regeneration in neotenic or paedomorphic urodeles.
与蝾螈不同，有尾目动物的绿蟾蜍完成两次变态，从水生环境中出现并交配成为完全陆生的成体。幼虫和成虫肢体再生通常被视为大致等同的过程，并且至少在一定程度上是胚胎发育的重演。
我们比较了幼虫肢体发育与幼虫和成虫前肢的再生，发现幼虫和成虫在发育模式上存在显著差异。在成年再生体中，前轴优势的幼虫模式不存在：成年再生体同步发育指，在近端附肢原基形成离散聚集区之前就开始了。相比之下，幼虫再生体遵循从前到后的顺序形成指的模式，就像它们的胚胎肢芽一样。
基于这些形态学线索，我们得出结论，幼虫再生体不太可能表现出成年体中出现的表型再生特征，而更可能代表一种发育调控形式。此外，我们证实，后变态肢体再生在形态学水平上不是本体论的简单重演。这些区别可能有助于解释和解释一些关于幼态持续或幼态发生的有尾类动物再生的实验和观察。
