Development of an in vitro Ovary Culture System to Evaluate Endocrine Disruption in Wood Frog Tadpoles

Abstract

Gonad–mesonephros complexes from wood frog (Lithobates sylvaticus) tadpoles were incubated in vitro for 1 wk to examine direct effects of naphthenic acids (NA) and 17α-ethinylestradiol (EE2) on ovarian differentiation. Histological images reveal successful preservation of gonadal integrity where cultured oocytes exhibited no significant differences in diameters and areas compared to uncultured conditions. Ovaries exposed to 10 μg/L 17α-EE2 contained oocytes with significantly advanced atresia and diminished areas and diameters, indicating a degree of ovarian regression. A significant reduction in oocyte area was observed in ovaries exposed to 3 mg/L of a commercial extract of petroleum-derived NA. This novel approach has applications for screening direct effects of endocrine-disrupting chemicals on gonadal function in tadpoles.

Additional information

Funding

The help of Bill Fletcher and Christine Archer from the aquatic facility at the University of Ottawa is greatly appreciated. The assistance of Lorraine Casavant and Mike Wade from Health Canada for histological processing, and of Julie Bilodeau and Nicholas Kim for tadpole dissections, is acknowledged. Funding from the University of Ottawa Research Chair program supported this work. Current affliaition for Laia Navarro-Martín is Institute of Environmental Assessment and Water Research, IDAEA-CSIC, Barcelona, Spain.