Reproductive dysgenesis in wildlife: a comparative view

Area of Science:

• Reproductive toxicology
• Environmental health
• Comparative endocrinology

Background:

• Abnormal male reproductive development, termed testicular dysgenesis syndrome (TDS), is linked to environmental contaminant exposure across vertebrates, including humans and wildlife.
• TDS encompasses conditions like cryptorchidism, reduced semen quality, hypospadias, and testicular cancer, representing demasculinization or feminization of the male phenotype.

Purpose of the Study:

• To review and present examples of TDS in comparative species.
• To propose an ontogenetic model for TDS, highlighting early embryonic origins.

Main Methods:

• Review of existing literature on environmental contaminant exposure and reproductive abnormalities in wildlife and human models.
• Comparative analysis of TDS symptoms across diverse vertebrate species.

Main Results:

• Wildlife species exposed to environmental contaminants exhibit reproductive abnormalities similar to human TDS, with some non-mammalian species showing greater feminization due to higher reproductive plasticity.
• Oocytes developing within testes were observed in some species, indicating severe feminization.

Conclusions:

• Male susceptibility to environmental contaminants causing TDS originates in the sexually undifferentiated embryonic stage.
• Bipotential reproductive tissues in embryos are susceptible to environmental influences, directing development towards male or female phenotypes.