Comparative Histolab Padua, Department of Biology, University of Bologna, Bologna 40126, Italy; E-mail:
Zool Res. 2018 Nov 18;39(6):413-423. doi: 10.24272/j.issn.2095-8137.2018.050. Epub 2018 Jul 6.
Lizards are key amniote models for studying organ regeneration. During tail regeneration in lizards, blastemas contain sparse granulocytes, macrophages, and lymphocytes among the prevalent mesenchymal cells. Using transmission electron microscopy to examine scarring blastemas after third and fourth sequential tail amputations, the number of granulocytes, macrophages, and lymphocytes increased at 3-4 weeks in comparison to the first regeneration. An increase in granulocytes and agranulocytes also occurred within a week after blastema cauterization during the process of scarring. Blood at the third and fourth regeneration also showed a significant increase in white blood cells compared with that under normal conditions and at the first regeneration. The extracellular matrix of the scarring blastema, especially after cauterization, was denser than that in the normal blastema and numerous white blood cells and fibroblasts were surrounded by electron-pale, fine fibrinoid material mixed with variable collagen fibrils. In addition to previous studies, the present observations support the hypothesis that an increase in inflammation and immune reactions determine scarring rather than regeneration. These new findings verify that an immune reaction against mesenchymal and epidermal cells of the regenerative blastema is one of the main causes for the failure of organ regeneration in amniotes.
蜥蜴是研究器官再生的关键羊膜动物模型。在蜥蜴的尾巴再生过程中，芽基中除了普遍存在的间充质细胞外，还含有稀疏的粒细胞、巨噬细胞和淋巴细胞。通过透射电子显微镜检查第三次和第四次连续尾巴截肢后的疤痕芽基，与第一次再生相比，在 3-4 周时粒细胞、巨噬细胞和淋巴细胞的数量增加。在疤痕形成过程中，芽基烧灼后一周内粒细胞和无粒细胞也会增加。与正常情况和第一次再生相比，第三次和第四次再生时血液中的白细胞数量也明显增加。与正常芽基相比，疤痕芽基的细胞外基质（尤其是烧灼后）更加致密，许多白细胞和成纤维细胞被电子淡染的细纤维蛋白样物质包围，其中混合有不同的胶原纤维。除了之前的研究，本观察结果支持以下假说：炎症和免疫反应的增加决定了疤痕的形成，而不是再生。这些新发现证实，针对再生芽基的间充质和表皮细胞的免疫反应是羊膜动物器官再生失败的主要原因之一。
