Alibardi Lorenzo
Comparative Histolab, Padua, Italy.
Dipartimento Di Biologia, Universita Di Bologna, via Selmi 3, 40126, Bologna, Italy.
Protoplasma. 2022 Jul;259(4):981-998. doi: 10.1007/s00709-021-01711-4. Epub 2021 Oct 25.
The development of scales and the sequence of epidermal layers during snake embryogenesis has been studied by immunofluorescence for the localization of cell adhesion, adherens, and communicating cell junctional proteins. At about 2nd/3rd of embryonic development in snakes the epidermis forms symmetric bumps at the beginning of scale formation, and they rapidly become asymmetric and elongate forming outer and inner surfaces of the very overlapped scales seen at hatching. The dermis separates a superficial loose from a deeper dense part; the latter is joined to segmental muscles and nerves, likely acting on scale orientation during snake movements. N-cam is present in the differentiating epidermis and mesenchyme of forming scales while L-cam is only/mainly detected in the periderm and epidermis. Mesenchymal N-cam is associated with the epidermis of the elongating dorsal scale surface and with the beta-differentiation that occurs in the overlapping outer surface of scales. Beta-catenin and Connexin-43 show a similar distribution, and they are mainly present in the periderm and differentiating suprabasal keratinocytes likely forming an intense connectivity during epidermal differentiation. Beta-catenin also shows nuclear localization in differentiating cells of the shedding and beta-layers at late stages of scale morphogenesis, before hatching. The study suggests that intensification of adhesion and gap junctions allows synchronization of the differentiation of suprabasal cells to produce the ordered sequence of epidermal layers of snake scales, starting from the shedding complex and the beta-layer.
通过免疫荧光法对细胞黏附、黏附连接和通讯细胞连接蛋白进行定位,研究了蛇胚胎发育过程中鳞片的发育和表皮层的顺序。在蛇胚胎发育的大约2/3阶段,表皮在鳞片形成开始时形成对称的凸起,随后迅速变得不对称并伸长,形成孵化时所见的高度重叠鳞片的外表面和内表面。真皮将浅层疏松部分与深层致密部分分开;后者与节段性肌肉和神经相连,可能在蛇运动时对鳞片方向起作用。N-cam存在于正在分化的表皮和形成鳞片的间充质中,而L-cam仅/主要在周皮和表皮中检测到。间充质N-cam与伸长的背侧鳞片表面的表皮以及鳞片重叠外表面发生的β分化相关。β-连环蛋白和连接蛋白-43显示出相似的分布,它们主要存在于周皮和正在分化的基底上层角质形成细胞中,可能在表皮分化过程中形成紧密的连接。在孵化前鳞片形态发生的后期,β-连环蛋白在蜕皮层和β层的分化细胞中也显示出核定位。该研究表明,黏附连接和缝隙连接的增强使得基底上层细胞的分化同步,从而从蜕皮复合体和β层开始产生蛇鳞片表皮层的有序序列。