title: The fertility of bulls born twin to freemartins: a review.
abstract: Evidence for the existence of XX germ cells in the testes of bulls born twin to females is reviewed. It is concluded that there is probably no shift in the sex ratio of the offspring in favour of females. Reports on the fertility of such bulls are reviewed. It is suggested that, provided the semen is normal, there is no reason why such a bull should not be used for breeding purposes.
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D005298:Fertility; D005611:Freemartinism / Q000235:genetics*; D008297:Male; D011247:Pregnancy; D012744:Sex Ratio; D014427:Twins; D014960:X Chromosome