Induction of vitellogenin synthesis by nonylphenol and 17β-estradiol and effects on the testicular structure in the eelpout Zoarces viviparus

In the present study the effect of nonylphenol or 17β-estradiol on vitellogenin synthesis and testicular structure was investigated in male eelpouts Zoarces viviparus during active spermatogenesis (May) and at late spermatogenesis (June). Nonylphenol or estradiol treatment resulted in a significant increase in the plasma vitellogenin concentration concomitant with a significant reduction in the gonadosomatic index. Histological examination revealed severe effects on the testis. Controls had seminiferous lobules containing spermatocysts (May) or cuboidal Sertoli cells (June). In treated fish, lobules were degenerated (May) or were filled with spermatozoa and had squamous Sertoli cells containing phagocytized sperm cells (June). The results indicate that nonylphenol is estrogenic and has marked effects on the testis of Zoarces viviparus.