Ultrastructure and histology of reproductive system in the free-living marine nematode (Oncholaimus campylocercoides) with reference to polychlorinated biphenyls (PCBs) pollution in Persian Gulf

polychlorinated biphenyls may affect their physiological process. The present study is conducted to describe physiological and histological pattern of marine nematode (Oncholaimus campylocercoides) from north Persian Gulf. Three locations with different concentrations of PCBs were selected in Bandar Abbas for sampling. Sex steroid hormones (progesterone, testosterone and 17-B estradiol) were analysed after separation and purification of marine nematodes from sediments. Moreover, fine structures of ovocyte and spermatozoa were studied after histological observation. Results showed that sex ratios were F(1): M(0.97), F(1): M (0.9), F(1): M(0.5) in locations with 0.01, 0.02 and 0.1 μg/mL tissue PCB concentrations, respectively. Level of 17 β-estradiol (1.2±0.07pg/mL) in females at the location with 0.1 μg/mL PCB (power plant) was significantly higher than that in other two sampling locations. Also high level of testosterone (0.4±0.07 pg/mL) was observed in males and females at the polluted sampling site compared with that in other two locations. Histological study showed that in the location with high PCBs, there was an obvious increase in size of oocytes. We concluded that PCBs can affect sex steroid changes as endocride disruptors in Oncholaimus campylocercoides. Results of this study supporte