Intersexes and sex determination in chickens.

Chickens sexed as females in commercial flocks show a low frequency of intersex individuals. Gross anatomical examination of the intersexes revealed malformed gonads. Histological examination proved that these gonads were not ovotestes but were composed of testicular tissues. Karyotype analysis of 15 intersex individuals showed 13 of them to be 3A-ZZW triploids (normal females are 2A-ZW) while the other 2 were mosaic for male and female karyotypes. Red blood cell volume accurately reflects the ploidy level and is suggested for use in screening for polyploids. Intersex triploids may develop parthenogenetically or from fertilization between reduced and unreduced gametes.