Laboratory of Histology, Biosciences Institute, Faculty of Medicine and Pharmacy, University of Mons, Mons, Belgium.
J Morphol. 2021 Feb;282(2):230-246. doi: 10.1002/jmor.21298. Epub 2020 Nov 9.
Sand deserts are common biotopes on the earth's surface. Numerous morphological and physiological adaptations have appeared to cope with the peculiar conditions imposed by sandy substrates, such as abrasion, mechanical resistance and the potential low oxygen levels. The psammophilous scincids (Lepidosauria) Scincus scincus and Eumeces schneideri are among those. S. scincus is a species frequently used to study displacement inside a sandy substrate. E. schneideri is a species phylogenetically closely related to S. scincus with a similar lifestyle. The aims of this study focus on the morphology of the integument and the muscular system. Briefly, we describe interspecific differences at the superficial architecture of the scales pattern and the thickness of the integument. We highlight a high cellular turnover rate at the level of the basal germinal layer of the epidermis, which, we suggest, corresponds to an adaptation to cutaneous wear caused by abrasion. We demonstrate the presence of numerous cutaneous holocrine glands whose secretion probably plays a role in the flow of sand along the integument. Several strata of osteoderms strengthen the skin. We characterize the corporal (M. longissimus dorsi and M. rectus abdominus) and caudal muscular fibers using immunohistochemistry, and quantify them using morphometry. The musculature exhibits a high proportion of glycolytic fast fibers that allow rapid burying and are well adapted to this mechanically resistant and oxygen-poor substrate. Oxidative slow fibers are low in abundance, less than 10% in S. scincus, but a little higher in E. schneideri.
沙漠是地球表面常见的生物生境。为了应对沙质基质带来的特殊条件,如磨损、机械阻力和潜在的低氧水平,生物出现了许多形态和生理适应。沙生蜥蜴(有鳞目)石龙子属的石龙子和丽纹蛇蜥就是其中的代表。石龙子是一种经常被用于研究在沙质基质中位移的物种。丽纹蛇蜥与石龙子亲缘关系密切,生活方式也相似。本研究的目的集中在皮肤和肌肉系统的形态上。简而言之,我们描述了物种间在鳞片图案的表面结构和表皮厚度上的差异。我们强调了表皮基底层的高细胞周转率,我们认为这对应于对磨损引起的皮肤磨损的适应。我们还证明了大量皮肤全泌腺的存在,其分泌物可能在沙粒沿皮肤流动中发挥作用。数层骨板增强了皮肤的强度。我们使用免疫组织化学对躯体(背最长肌和腹直肌)和尾部肌肉纤维进行了特征描述,并使用形态计量学对它们进行了量化。肌肉组织表现出高比例的糖酵解快肌纤维,这使它们能够快速掩埋,并很好地适应这种机械阻力大、缺氧的基质。氧化慢肌纤维的丰度较低,石龙子中的含量不到 10%,而丽纹蛇蜥中的含量略高。