4-Octylphenol is a hormone disruptor that has gender-specific effects on male reproductive cells, significantly reducing the mitotic index and the number of spermatogonia. 4-Octylphenol can cause inflammatory damage to fish gills by activating the complement system through the C3a/C3aR axis and the C5a/C5aR1 axis, this leads to complement activation and causes immune suppression due to the imbalance between Th1/Th2 cells and regulatory T cells (Treg)/Th17 cells, as well as inflammatory damage via the Toll-like receptor 7 (Toll-like Receptor (TLR))/IkappaBalpha/NF-kappaB pathway[1][2].
