Alibardi Lorenzo
Comparative Histolab Padova, 35100 Padova, Italy.
Department of Biology, University of Bologna, 40126 Bologna, Italy.
J Dev Biol. 2023 Aug 14;11(3):35. doi: 10.3390/jdb11030035.
Here we report the immunolocalization of mucin, nestin, elastin and three glycoproteins involved in tissue mineralization in small and large juveniles of . Both small and larger juvenile epidermis are mucogenic and contain a diffuse immunolabeling for nestin. Sparse PCNA-labeled cells, indicating proliferation, are found in basal and suprabasal epidermal layers. No scales are formed in small juveniles but are present in a 5 cm long juvenile and in larger juveniles. Elastin and a mineralizing matrix are localized underneath the basement membrane of the tail epidermis where lepidotriches are forming. The latter appears as "circular bodies" in cross sections and are made of elongated cells surrounding a central amorphous area containing collagen and elastin-like proteins that undergo calcification as evidenced using the von Kossa staining. However, the first calcification sites are the coniform teeth of the small juveniles of 2-3 cm in length. In the superficial dermis of juveniles (16-26 cm in length) where scales are formed, the spinulated outer bony layer (squamulin) of the elasmoid scales contains osteonectin, alkaline phosphatase, osteopontin, and calcium deposits that are instead absent in the underlying layer of elasmodin. In particular, these glycoproteins are localized along the scale margin in juveniles where scales grow, as indicated by the presence of PCNA-labeled cells (proliferating). These observations suggest a continuous deposition of new bone during the growth of the scales, possibly under the action of these mineralizing glycoproteins, like in the endoskeleton of terrestrial vertebrates.
在此，我们报告了在[具体物种]大小不同的幼年个体中粘蛋白、巢蛋白、弹性蛋白以及三种参与组织矿化的糖蛋白的免疫定位情况。大小不同的幼年个体表皮均具有粘蛋白生成能力，且对巢蛋白呈现弥漫性免疫标记。在基底和基底上层表皮层中发现了稀疏的增殖细胞核抗原（PCNA）标记细胞，表明存在细胞增殖。小的幼年个体未形成鳞片，但在体长5厘米的幼年个体及更大的幼年个体中存在鳞片。弹性蛋白和矿化基质定位于尾表皮基底膜下方，此处正在形成鳞片。后者在横切面上呈现为“圆形体”，由围绕中央无定形区域的细长细胞组成，该区域含有胶原蛋白和类弹性蛋白，经冯·科萨染色证实会发生钙化。然而，最早的钙化部位是体长2 - 3厘米的小幼年个体的锥形齿。在形成鳞片的幼年个体（体长16 - 26厘米）的浅表真皮中，硬鳞的具刺状外层骨层（鳞质）含有骨连接蛋白、碱性磷酸酶、骨桥蛋白和钙沉积物，而在其下方的弹性蛋白层中则不存在这些物质。特别是，这些糖蛋白定位于鳞片生长的幼年个体的鳞片边缘，增殖细胞核抗原（PCNA）标记细胞（正在增殖）的存在表明了这一点。这些观察结果表明，在鳞片生长过程中可能在这些矿化糖蛋白的作用下持续有新骨沉积，类似于陆地脊椎动物的内骨骼。
