Feminizing/demasculinizing effects of polychlorinated biphenyls on the secondary sexual development of Xenopus laevis.
We have previously demonstrated that polychlorinated biphenyls (PCBs) have caused phenotypic feminization/demasculinization of gonadal development in Xenopus laevis. Whether PCBs affect secondary sexual development has remained unknown. In this study, X. laevis tadpoles were exposed to Aroclor1254 and PCB(3) from stage 46/47 (system of Nieuwkoop and Faber) for up to 1 month postmetamorphosis. After 24 months postmetamorphosis, the degree of secondary sexual development was examined. Male oviducts were observed in some of the PCB-exposed male frogs, but not in control males. These male oviducts had not completely developed in histological structure when compared with mature female oviducts. Larynx weight and width of PCB-exposed males were significantly less than those of control males. Laryngeal histology showed that PCBs inhibited cartilaginous and muscular development of male frogs, i.e. elastic cartilages had not completely developed and laryngeal muscle fibers were smaller. In a further study on adult male frogs, a decrease in serum testosterone level was found in PCB-exposed frogs compared with controls, but serum estradiol level was not significantly affected. Our study suggests that PCBs can cause phenotypic feminization/demasculinization of male genital ducts and larynges, and these effects may, in part, result from the decrease in serum testosterone level in X. laevis.
Qin
Zhan-Fen
ZF
The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, The Chinese Academy of Sciences, Beijing, China. Electronic address: qinzhanfen@rcees.ac.cn.
Qin
Xiao-Fei
XF
The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, The Chinese Academy of Sciences, Beijing, China.
Yang
Lei
L
The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, The Chinese Academy of Sciences, Beijing, China.
Li
Han-Ting
HT
The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, The Chinese Academy of Sciences, Beijing, China.
Zhao
Xing-Ru
XR
The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, The Chinese Academy of Sciences, Beijing, China.
Xu
Xiao-Bai
XB
The State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, The Chinese Academy of Sciences, Beijing, China.
D000818:Animals; D020111:Chlorodiphenyl (54% Chlorine) / Q000633:toxicity*; D004785:Environmental Pollutants / Q000633:toxicity*; D004958:Estradiol / Q000097:blood; D005260:Female; D005262:Feminization / Q000097:blood / Q000139:chemically induced*; D006651:Histocytochemistry; D007830:Larynx / Q000187:drug effects; D008297:Male; D008675:Metamorphosis, Biological / Q000187:drug effects*; D010641:Phenotype; D046468:Sexual Development / Q000187:drug effects*; D013739:Testosterone / Q000097:blood; D014982:Xenopus laevis / Q000097:blood / Q000254:growth & development*
D004785:Environmental Pollutants; D020111:Chlorodiphenyl (54% Chlorine); D013739:Testosterone; D004958:Estradiol