Payne Samantha L, Peacock Hanna M, Vickaryous Matthew K
Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
J Morphol. 2017 Mar;278(3):380-389. doi: 10.1002/jmor.20648. Epub 2017 Jan 12.
Unique among amniotes, many lizards are able to self-detach (autotomize) their tail and then regenerate a replacement. Tail regeneration involves the formation of a blastema, an accumulation of proliferating cells at the site of autotomy. Over time, cells of the blastema give rise to most of the tissues in the replacement tail. In non-amniotes capable of regenerating (such as urodeles and some teleost fish), the blastema is reported to be essentially avascular until tissue differentiation takes place. For tail regenerating lizards less is known. Here, we investigate neovascularization during tail regeneration in the leopard gecko (Eublepharis macularius). We demonstrate that the gecko tail blastema is not an avascular structure. Beginning with the onset of regenerative outgrowth, structurally mature (mural cell supported) blood vessels are found within the blastema. Although the pattern of blood vessel distribution in the regenerate tail differs from that of the original, a hierarchical network is established, with vessels of varying luminal diameters and wall thicknesses. Using immunostaining, we determine that blastema outgrowth and tissue differentiation is characterized by a dynamic interplay between the pro-angiogenic protein vascular endothelial growth factor (VEGF) and the anti-angiogenic protein thrombospondin-1 (TSP-1). VEGF-expression is initially widespread, but diminishes as tissues differentiate. In contrast, TSP-1 expression is initially restricted but becomes more abundant as VEGF-expression wanes. We predict that variation in the neovascular response observed between different regeneration-competent species likely relates to the volume of the blastema. J. Morphol. 278:380-389, 2017. © 2017 Wiley Periodicals, Inc.
在羊膜动物中，许多蜥蜴具有独特的能力，能够自行断尾（自割），然后再生出一条新尾巴。尾巴再生涉及芽基的形成，芽基是在自割部位积累的增殖细胞。随着时间的推移，芽基中的细胞产生了再生尾巴中的大部分组织。据报道，在能够再生的非羊膜动物（如蝾螈和一些硬骨鱼）中，芽基在组织分化之前基本是无血管的。对于能够再生尾巴的蜥蜴，人们了解得较少。在这里，我们研究豹纹守宫（Eublepharis macularius）尾巴再生过程中的新血管形成。我们证明，守宫尾巴芽基不是无血管结构。从再生生长开始，在芽基内就发现了结构成熟（有壁细胞支持）的血管。虽然再生尾巴中的血管分布模式与原来的不同，但建立了一个分层网络，有不同管腔直径和壁厚的血管。通过免疫染色，我们确定芽基生长和组织分化的特征是促血管生成蛋白血管内皮生长因子（VEGF）和抗血管生成蛋白血小板反应蛋白-1（TSP-1）之间的动态相互作用。VEGF表达最初广泛存在，但随着组织分化而减少。相反，TSP-1表达最初受到限制，但随着VEGF表达减弱而变得更加丰富。我们预测，在不同再生能力物种之间观察到的新血管反应差异可能与芽基的体积有关。《形态学杂志》278:380 - 389，2017年。© 2017威利期刊公司。
