Toxicology

Defective Reproductive Organ Morphology and Function in Domestic Rooster Embryonically Exposed to o,p^'-DDT or Ethynylestradiol

Abstract
Environmental pollutants with estrogenic activity have a potential to disrupt estrogen-dependent developmental processes. The objective of this study was to investigate if embryonic exposure to the environmental estrogens o,p^'-DDT (1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2,2-trichloroethane; 37, 75, 150 or 300 µg/g egg) or EE₂ (17alpha- ethynylestradiol; 60 ng/g egg) affects the reproductive system in domestic roosters. Following egg-injection on embryonic day four, the newly hatched chicks were sexed by cloacal inspection. A skewed phenotypic sex ratio with overrepresentation of chicks deemed as females was observed in the groups exposed to the three highest doses of o,p^'-DDT but not in the EE₂-exposed group. Normal sex ratios were observed in all groups at adulthood. However, a cloacal deformation seemed to remain in the adult roosters causing an abnormal semen flow upon semen collection. Semen yield was significantly reduced in both o,p^'-DDT - and EE₂- exposed birds. Sperm motility and fertilizing ability in vitro were unaffected. At sacrifice, deformations of the left testis were found in all treatment groups. Image analysis revealed a reduced seminiferous tubular area in the roosters exposed to the two highest doses of o,p^'-DDT. Embryonic exposure to o,p^'-DDT caused decreased comb weight and right spur diameter while EE₂ only affected right spur diameter. In conclusion, this study shows that embryonic exposure to estrogenic compounds can induce permanent effects in male birds. The effects of the two studied compounds were partly similar but o,p^'-DDT also induced alterations not seen in the EE₂-treated birds.

Key words: Embryo • Testis • Toxicology • Epididymis • Estradiol

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