Sex reversed chicks (Gallus domesticus) hatched from eggs treated with aromatase inhibitor YM511

Abstract

The objectives of this study were to assess post-hatch development of chickens treated in ovo with the aromatase inhibitor YM511. A total of 137 eggs coming from artificially inseminated hens were at first injected in the albumen with either DMSO alone (54 eggs injected, control group) or with DMSO + aromatase inhibitor (YM511, 1 mg/egg, 83 eggs injected, treated group) and then incubated under standard conditions. Out of the 24 chicks hatched in the treated group, 16 were genetic males (ZZ) and 8 were genetic females (ZW). By 26 weeks of age, secondary sex characteristics of females (cloaca, comb, wattles, song, feathers of hackle and tail) progressively transformed into a male phenotype. Using CT-scanner technology in these 8 birds, the presence of irregular testis-like masses positioned in the antero-ventral portion of the kidneys was observable, an indication that reproductive organs had also been affected by the treatment.