Fish gills are heavily exposed to the external milieu and may react against irritants with different cellular responses. We describe variations in mucous cell counts in gills from healthy Atlantic salmon (Salmo salar) presmolts in five recirculating aquaculture system (RAS) farms and one flow‐through farm. Based on certain criteria, mucous cells were histologically quantified in a defined lamellar region of the gills and the counts were analysed. Immunohistochemistry (IHC) was used to investigate epithelial responses. The median number of total mucous cells in the defined region was 59 per fish. Between the farms, the medians varied from 31 to 101 with the lowest in the flow‐through farm. A regression model was fitted with “total mucous cells” as the dependent variable and with “fish length” and “fish farm” as independent variables. The proportion of variation in mucous cell counts explained by the model was twice as high when “fish farm” was included compared to only “fish length.” IHC revealed proliferative responses in coherence with high mucous cell numbers. Conclusively, the variation in mucous cell counts depends on combined farm‐related factors. Establishing a baseline for mucous cell counts is fundamental in the development of high‐throughput monitoring programmes of gill health in farmed fish.

中文翻译：

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挪威商业淡水养殖场中大西洋鲑（Salmo salar）前体mol的黏液细胞数量变化

鱼g严重暴露在外部环境中，可能对具有不同细胞反应的刺激物产生反应。我们描述了健康大西洋鲑（Salmo salar）g的黏液细胞计数变化）在五个循环水产养殖系统（RAS）养殖场和一个直通式养殖场中进行预育。根据某些标准，在a的确定的层状区域中对粘液细胞进行组织学定量，然后对计数进行分析。免疫组织化学（IHC）用于研究上皮反应。在限定区域中，每条鱼的总粘液细胞中位数为59。在农场之间，中位数从31到101不等，在流通农场中最低。回归模型以“总粘液细胞”为因变量，以“鱼类长度”和“养鱼场”为自变量进行拟合。该模型解释的粘液细胞计数变化比例在包括“养鱼场”时是“仅鱼长”的两倍。IHC揭示了与高粘液细胞数量相一致的增殖反应。总之，粘液细胞计数的变化取决于与农场相关的综合因素。建立粘液细胞计数基线是开发养殖鱼类fish健康的高通量监测计划的基础。