Quantitative analysis of ovarian surface photographs as a tool for assessment of chemical effects on folliculogenesis and ovulation in rats.

Female reproductive toxicity assessments rely on histological evaluation of ovaries by hematoxylin & eosin (H&E)-stained cross-sections. This is time-consuming, labor-intensive and costly, thus alternative methods for ovarian toxicity assessment could be valuable. Here, we report on an improved method based on quantification of antral follicles (AF) and corpora lutea (CL) using ovarian surface photographs, called 'surface photo counting' (SPC). To validate a potential utility for the method to detect effects on folliculogenesis in toxicity studies, we investigated ovaries from rats exposed to two well-known endocrine disrupting chemicals (EDCs), diethylstilbestrol (DES) and ketoconazole (KTZ). Animals were exposed to DES (0.003, 0.012, 0.048 mg/kg body weight (bw)/day) or KTZ (3, 12, 48 mg/kg bw/day) during puberty or adulthood. At the end of the exposure, ovaries were photographed under stereomicroscope and subsequently processed for histological assessments to allow for direct comparison between the two methods by quantifying AF and CL. There was a significant correlation between the SPC and histology methods, albeit CL counts correlated better than AF counts, potentially due to their larger size. Effects of DES and KTZ were found by both methods, suggesting applicability of the SPC method to chemical hazard and risk assessment. Based on our study, we propose that SPC can be employed as a fast and cheap tool for assessment of ovarian toxicity in in vivo studies to prioritize chemical exposure groups for further histological assessment.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Pauliina Damdimopoulou, Terje Svingen reports financial support was provided by European Union’s Horizon 2020 research and innovation programme “FREIA”.
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