Melanomacrophage centres (MMCs) play a key role in the immune response in fish. They are considered sensitive bio-monitoring structures with roles in the assessment of toxicant impacts. The aim of this study was to examine the potential histopathological effect of 4-nonylphenol (4-NP) on hepatic MMCs in Clarias gariepinus. To achieve this objective, adult male fish were divided randomly and equally into two groups: a control group and a group that was exposed to 4-NP (dissolved in water at a dose of 0.1 mg/L) for 21 days. The 4-NP-intoxicated hepatic MMCs contained numerous necrotic macrophages. Superoxide dismutase 2 was immuno-expressed in the hepatic MMCs in both groups, with no significant difference. Histomorphometric examination revealed that the sizes and numbers of MMCs were dramatically higher in the livers of 4-NP-exposed C. gariepinus than in control fish. Following 4-NP challenge, in the liver, the abundance of lipofuscin and haemosiderin pigments increased, and single-pigmented macrophages, aggregated groups of deformed red blood cells (RBCs) and macrophages were present near blood vessels and hepatic sinusoids. These results reveal that 4-NP exerts immunological effects on hepatic MMCs in C. gariepinus and support the utility of MMCs as a cytological biomarker for aquatic exposure to 4-NP.

黑色素巨噬细胞中心（MMCs）在鱼类的免疫反应中起关键作用。它们被认为是敏感的生物监测结构，在评估有毒物质的影响中起作用。这项研究的目的是检查4-壬基酚（4-NP）对加里氏鞭毛虫肝MMC的潜在组织病理学影响。。为了实现这一目标，将成年雄鱼随机分为两组：对照组和暴露于4-NP（以0.1 mg / L的剂量溶于水中）达21天的一组。4-NP中毒的肝MMC包含大量坏死性巨噬细胞。两组肝MMC中均超表达超氧化物歧化酶2，差异无统计学意义。组织形态计量学检查显示，在暴露于4-NP的C. gariepinus肝脏中，MMC的大小和数量显着增加而不是对照鱼。4-NP攻击后，肝脏中的脂褐素和血红素色素丰富，并且在血管和肝正弦曲线附近出现了单色素巨噬细胞，变形红细胞（RBC）和巨噬细胞的聚集群。这些结果表明4-NP对加里螺旋藻中的肝MMC发挥免疫学作用，并支持MMC作为水生暴露于4-NP的细胞生物学标志物的效用。