Ovarian follicle counts as a potential reproductive toxicity endpoint in small cetaceans: an explorative study of the ovarian form and function in harbour porpoises (Phocoena phocoena) and common dolphins (Delphinus delphis)

Bianca Melita Palmas

Marine mammals are sentinels of the ocean and human health, being top predators with long life span, they bioaccumulate lipophilic contaminants in their blubber layer likely to develop chronic diseases, developmental disorders, and reproductive failure. Comprehensive reproductive toxicity studies in small cetaceans are still hindered by the lack of valid quantitative and qualitative measurements of the toxic effect of pollutants on their reproductive capacity.
Ovarian follicular counting (oocyte quantification) has been identified as an endpoint marker for the assessment of female reproductive toxicity in humans and other mammals, where the effects of contaminants are assessed against the number of primordial and primary follicles. To undertake this approach, assessment of ovarian form and function is required, particularly in small cetacean species that exhibit marked ovarian asymmetry, such as the harbour porpoise (Phocoena phocoena).
This study using histological analysis, image acquisition and analysis software to investigate ovarian form and function on a set of stranded neonatal and juvenile harbour and common dolphin (Delphinus delphis) aimed to evaluate (1) ovarian asymmetry and development, and (2) establish a method for quantifying ovarian follicular numbers that could be used as a potential endpoint for assessments of reproductive in small cetacean studies.