Hereditary persistent right oviduct in the chicken PNP/DO line

Hereditary, persistent, right oviduct manifested in an inbred line (PNP/DO Line) from the Fayoumi breed of chickens was investigated for form of expre ssion and mode of inheritance. Females in the PNP/DO line have varying leng ths of elongated right oviducts, besides the normal left ovary, and oviduct s that generally possess, irrespective of their total length, regions simil ar to those normally observed in a left oviduct. Observations of embryos in dicated that the existence of right oviduct in this line could be attribute d to the slow regression of right Mullerian duct during the embryonic stage , and left-right asymmetry in female genital system is intrinsic in this li ne. Intracrosses of the PNP/DO line produced 93% of female embryos with per sistent right Mullerian ducts at the next generation, and reciprocal crosse s of the PNP/DO line and control strains produced 5 and 30% of female embry os with persistent right Mullerian ducts in the F-1 and N-2 generations, re spectively. Mating results suggested that this mutant trait is controlled b y two pairs of autosomal recessive genes with major effects and numerous lo ci that have minor effects. Thus, expression of this trait is due to the in teraction of major loci and the background genotype.