Origin and early evolution of regeneration mechanisms remain among the most pressing questions in animal regeneration biology. Porifera have exceptional regenerative capacities and, as early Metazoan lineage, are a promising model for studying evolutionary aspects of regeneration. Here, we focus on reparative regeneration of the body wall in the Mediterranean demosponge Aplysina cavernicola. The epithelialization of the wound surface is completed within 2 days, and the wound is completely healed within 2 weeks. The regeneration is accompanied with the formation of a mass of undifferentiated cells (blastema), which consists of archaeocytes, dedifferentiated choanocytes, anucleated amoebocytes, and differentiated spherulous cells. The main mechanisms of A. cavernicola regeneration are cell dedifferentiation with active migration and subsequent redifferentiation or transdifferentiation of polypotent cells through the mesenchymal-to-epithelial transformation. The main cell sources of the regeneration are archaeocytes and choanocytes. At early stages of the regeneration, the blastema almost devoid of cell proliferation, but after 24 hr postoperation (hpo) and up to 72 hpo numerous DNA-synthesizing cells appear there. In contrast to intact tissues, where vast majority of DNA-synthesizing cells are choanocytes, all 5-ethynyl-2'-deoxyuridine-labeled cells in the blastema are mesohyl cells. Intact tissues, distant from the wound, retains intact level of cell proliferation during whole regeneration process. For the first time, the apoptosis was studied during the regeneration of sponges. Two waves of apoptosis were detected during A. cavernicola regeneration: The first wave at 6-12 hpo and the second wave at 48-72 hpo.

中文翻译：

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介壳虫（Porifera）再生过程中的转分化和间充质到上皮的过渡。

再生机制的起源和早期进化仍然是动物再生生物学中最紧迫的问题。Porifera具有卓越的再生能力，作为后生动物的早期世系，是研究再生进化方面的有前途的模型。在这里，我们专注于地中海人体海绵Aplysina Cavernicola中体壁的修复性再生。伤口表面的上皮化在2天内完成，伤口在2周内完全愈合。再生伴随着大量未分化细胞（胚泡）的形成，该细胞由考古细胞，去分化的软骨细胞，无核变形细胞和分化的球状细胞组成。A.主要机制 肾小球囊再生是具有活动迁移的细胞去分化，以及通过间充质到上皮转化的多能细胞随后的再分化或转分化。再生的主要细胞来源是古细菌细胞和软骨细胞。在再生的早期，胚细胞几乎没有细胞增殖，但是在术后24小时（hpo）和长达72 hpo之后，那里出现了许多DNA合成细胞。与完整的组织不同，完整的组织中绝大多数的DNA合成细胞是软骨细胞，胚泡中所有5-乙炔基-2'-脱氧尿苷标记的细胞都是中磺酰基细胞。远离伤口的完整组织在整个再生过程中保持完整水平的细胞增殖。首次在海绵再生过程中研究了细胞凋亡。