Nonylphenol affects the granulation pattern of epidermal mucous cells in rainbow trout, Oncorhynchus mykiss

Nonylphenol is a biodegradation product of nonionic surfactants and has rec ently attracted considerable attention due to its estrogenic potential. Sex ually mature male rainbow trout mere repeatedly exposed (one to four period s of 10 days each) to environmentally relevant concentrations of nonylpheno l (1 mu g/L, 10 mu g/L) and for comparison, trout were injected,vith estrad iol. Since estrogens are known to induce structural changes within the fish skin, a similar effect of xenobiotics with estrogen-like activity was assu med. Samples of skin were evaluated by means of light and electron microsco py and histochemistry. In trout exposed to nonylphenol and to estradiol, th e structure of the epidermis was altered: an irregular overall architecture was often accompanied by detached pavement cells, vacuolation of the cytop lasm, and severely deformed cell nuclei. However, the granulation pattern o f the mucous cells was influenced exclusively after exposition to nonylphen ol. The number of large and irregularly shaped mucosomes depended more on t he exposure period than on the concentration of nonylphenol. Furthermore, t his alteration has not yet been reported for any other pollutant or stresso r and, thus, can be classified as an effect that would strongly indicate ex posure to nonylphenol. (C) 2000 Academic Press.