Despite reports that sharks have an exceptional capacity to heal from traumatic injuries, no detailed microscopic observations of integumental wounds have been reported for sharks. This study details the histopathological features of such wounds in a free-ranging shark. An adult male blacktip shark Carcharhinus limbatus was collected in 2017 during fisheries-independent sampling efforts in the coastal southeastern U.S. Atlantic. The shark had numerous lesions on his head, torso, and left pectoral fin that were compatible with shark bites. Representative samples from two wounds on the head were examined by light microscopy. The epidermal changes included hyperplasia and hypertrophy, intracellular edema, and absence of goblet cells, denticles, and chromatophores. In the dermis, fibrinocellular exudation, granulation tissue, and marked skeletal muscle necrosis and regeneration were observed. The above features were comparable with wound healing in bony fish, albeit minor differences were found. Although this case documents exceptionally good regeneration of skeletal muscle in the shark, we found no evidence of unique morphological healing patterns. Further studies on wound healing are needed because recent molecular and genetic findings do suggest evolutionary adaptations enhancing healing in sharks.

中文翻译：

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来自美国东南部大西洋沿岸的自由放养的黑鳍鲨 Carcharhinuslimbatus 皮肤伤口愈合的组织学观察：病例报告

尽管有报道称鲨鱼具有从外伤中愈合的特殊能力，但没有报道对鲨鱼的外皮伤口进行详细的显微镜观察。这项研究详细介绍了自由放养鲨鱼中此类伤口的组织病理学特征。2017 年，在美国大西洋东南部沿海的渔业独立采样工作中收集了一只成年雄性黑鳍鲨 Carcharhinuslimbatus。这条鲨鱼的头部、躯干和左胸鳍有许多与鲨鱼咬伤相符的损伤。通过光学显微镜检查来自头部两个伤口的代表性样品。表皮变化包括增生肥大、细胞内水肿以及杯状细胞、小齿和色素细胞的缺失。在真皮层，纤维蛋白细胞渗出，肉芽组织，并观察到明显的骨骼肌坏死和再生。上述特征与硬骨鱼的伤口愈合相当，尽管发现了细微的差异。虽然这个案例记录了鲨鱼骨骼肌的非常好的再生，但我们没有发现独特的形态愈合模式的证据。需要对伤口愈合进行进一步研究，因为最近的分子和遗传发现确实表明进化适应促进了鲨鱼的愈合。