title: Gonadal differentiation in frogs exposed to estrogenic and antiestrogenic compounds.
abstract: Exposure of amphibians to endocrine disrupting compounds (EDCs) may alter differentiation of gonads, especially when exposures begin during early life stages. Gonadal differentiation was observed in leopard frogs (Rana pipiens) and wood frogs (Rana sylvatica) exposed as tadpoles to estrogenic (estradiol, ethinylestradiol, nonylphenol) and antiestrogenic compounds (an aromatase inhibitor, flavone, and an antiestrogen, ICI 182780). Exposure to all compounds at micrograms/L concentrations altered gonadal differentiation in some animals by inducing either complete feminization or an intersex condition, and altered testicular tubule morphology, increased germ cell maturation (vitellogenesis), and oocyte atresia. Comparisons between the two species indicate that R. pipiens are more susceptible to sex reversal and development of intersex gonads. However, R. sylvatica also showed alterations to testicular morphology, germ cell maturation, and ooctye atresia. These laboratory results indicate that amphibians could be susceptible to altered gonadal differentiation and development when exposed to estrogenic and antiestrogenic compounds in aquatic environments, such as those impacted by agricultural, industrial, and municipal runoff.
authors.affiliation: Watershed Ecosystems Graduate Program, Trent University, Peterborough, Ontario, K9J 7B8, Canada.
authors.forename: Constanze A
authors.initials: CA
authors.lastname: Mackenzie
authors.forename: Michael
authors.initials: M
authors.lastname: Berrill
authors.forename: Chris
authors.initials: C
authors.lastname: Metcalfe
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Pauli
mesh_terms: D000818:Animals; D020847:Estrogen Receptor Modulators / Q000633:toxicity*; D004967:Estrogens / Q000633:toxicity*; D005260:Female; D047309:Flavones; D005419:Flavonoids / Q000633:toxicity; D006066:Gonads / Q000187:drug effects / Q000254:growth & development*; D007814:Larva / Q000254:growth & development; D008297:Male; D009865:Oocytes; D011894:Rana pipiens / Q000254:growth & development*; D011898:Ranidae / Q000254:growth & development*; D012733:Sex Differentiation / Q000187:drug effects*; D014818:Vitellogenesis / Q000187:drug effects; D014873:Water Pollutants / Q000633:toxicity*
chemical_list: D020847:Estrogen Receptor Modulators; D004967:Estrogens; D047309:Flavones; D005419:Flavonoids; D014873:Water Pollutants; C043562:flavone