The stratum corneum (SC), the top layer of the epidermis, is the functional site of the skin barrier and serves to maintain hydration of the body by preventing water loss and thwarting the entrance of pathogens. The naked mole rat (NMR) (Heterocephalus glaber) is a rodent that resides in hypoxic underground tunnels in arid Africa. NMRs are not only hairless; their skin is devoid of glands and pain sensation. To understand how the skin barrier of the NMR is uniquely adapted to this environment, skin samples from the dorsum and ventral abdomen in one adult and one neonate were examined by transmission electron microscopy using both reduced osmium tetroxide to assess overall structure and ruthenium tetroxide post‐fixation to assess lipid organization. These findings were compared with that of hairless mice—a well‐defined model for skin barrier studies. The plasticity of the skin was evaluated on 10 NMRs from a colony at the Philadelphia Zoo in humid and dry conditions by measuring cutaneous hydration, transepidermal water loss (TEWL), and pH. The epidermal ultrastructure of the NMR differed from hairless mice by having the following features: decreased content of lamellar bodies (LBs), higher LB pleomorphism, periodic presence of abnormal lipid bilayers, and an unusually thick SC. The NMRs developed significant TEWL and a trend toward decreased hydration when subjected to dry conditions. While these features illustrate an imperfect skin barrier in terrestrial mammals, they likely represent adaptations of the poikilothermic NMRs to their unique natural fossorial climate. Prolonged exposure to decreased humidity could possibly lead to adverse health effects in this species.

中文翻译：

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裸鼹鼠皮肤屏障的独特特征反映了对其化石栖息地的适应

角质层 (SC) 是表皮的顶层，是皮肤屏障的功能部位，通过防止水分流失和阻止病原体进入来维持身体的水分。裸鼹鼠 (NMR) (Heterocephalus glaber) 是一种栖息在非洲干旱缺氧地下隧道中的啮齿动物。核磁共振不仅无毛；他们的皮肤没有腺体和痛觉。为了了解核磁共振的皮肤屏障如何独特地适应这种环境，通过透射电子显微镜检查了来自一名成人和一名新生儿的背部和腹侧的皮肤样本，使用还原四氧化锇评估整体结构和四氧化钌后固定以评估脂质组织。将这些发现与无毛小鼠的发现进行了比较——这是一种用于皮肤屏障研究的明确模型。在潮湿和干燥条件下，通过测量皮肤水合作用、经皮水分流失 (TEWL) 和 pH 值，在费城动物园的一个菌落的 10 NMR 上评估皮肤的可塑性。NMR 的表皮超微结构与无毛小鼠的不同之处在于具有以下特征：层状体 (LB) 含量减少、LB 多形性更高、周期性存在异常脂质双层和异常厚的 SC。当经受干燥条件时，NMR 产生了显着的 TEWL 和水合减少的趋势。虽然这些特征说明陆生哺乳动物的皮肤屏障不完善，但它们可能代表了变温核磁共振对其独特的自然化石气候的适应。