Abstract Recent studies have shown that, despite stereotypical cleavage, annelids show the ability for embryonic regulation, including the formation of germline cells. However, the widest variety of regulative processes is presented in the postlarval development of annelids. The ability to regenerate, which is probably an ancestral feature, manifests itself variously among these animals. Some species are unable to regenerate lost segments. However, most species replace lost posterior body parts, many are able to reestablish missing head segments and structures, and some develop the entire body de novo even on the basis of one or two segments. Most of the regenerated structures are formed due to a set of undifferentiated cells arising from the division of dedifferentiated and/or stem cells. Moreover, the regeneration process often involves remodeling of survived body fragments and may thus be associated not only with local changes but also require a response at the level of the whole organism. In this review, we summarize many recent studies on the molecular and cellular mechanisms of regeneration in annelids. Special attention is paid to the regeneration of the digestive and nervous systems and integuments as well as to the involvement of stem and undifferentiated cells in the development of blastema and in replacing the lost gonads. Accumulation and analysis of recent findings about the diversity of cellular sources and mechanisms of annelid regeneration may shed light on the most evolutionarily conserved programs for maintaining regeneration ability and processes leading to the loss (limitation) of one of the ancestral features of animals.

中文翻译：

---

环节动物的再生：细胞来源、组织重塑和差异基因表达

摘要 最近的研究表明，尽管有刻板的分裂，环节动物显示出胚胎调节的能力，包括生殖细胞的形成。然而，环节动物的后期幼体发育中存在最广泛的调节过程。再生能力可能是祖先的特征，在这些动物中表现不同。一些物种无法再生丢失的片段。然而，大多数物种替换丢失的身体后部部分，许多能够重建丢失的头部节段和结构，有些甚至在一个或两个节段的基础上从头发育整个身体。大多数再生结构是由于去分化细胞和/或干细胞分裂产生的一组未分化细胞而形成的。而且，再生过程通常涉及幸存的身体碎片的重塑，因此可能不仅与局部变化有关，而且还需要在整个生物体的水平上做出反应。在这篇综述中，我们总结了许多最近关于环节动物再生的分子和细胞机制的研究。特别注意消化系统和神经系统和外皮的再生，以及干细胞和未分化细胞在胚泡发育和替换丢失的性腺中的参与。对有关环节动物再生的细胞来源和机制的多样性的最新发现的积累和分析可能会阐明在进化上最保守的程序，用于维持再生能力和导致动物祖先特征之一丧失（限制）的过程。