Demasculinisation of sexually mature male common carp, Cyprinus carpio, exposed to 4-tert-pentylphenol during spermatogenesis

Sexually mature male common carp (Cyprinus carpio) were exposed for a 3-month period to sublethal concentrations of 4-tert-pentylphenol (TPP) and to 17β-estradiol (E2) during spermatogenesis. This was part of a broad research programme investigating the effects of TPP on the life stages of the carp which might prove susceptible to endocrine disruption. Exposure of adult male carp to the pseudo-estrogen TPP, or to E2 during sexual maturation, led to elevated plasma levels of vitellogenin (P<0.001), a typically female protein and to the inhibition of the spermatogenesis. The histological examination of the testes showed the progressive disappearance of spermatozoa and spermatogenic cysts, and a higher incidence of pathological alterations with time at all TPP and E2 concentrations (e.g. fibrosis, vacuolation and atrophy of the germinal epithelium). A reduced diameter of the seminiferous lobules (P<0.001) was measured in fish testes exposed to all TPP concentrations for 3 months and in some TPP exposures, after 1 and 2 months. After a 3-month exposure, the spermatocrit values of fish exposed to the highest TPP concentration were significantly lower than those of the control (P