Head Skeletal Abnormalities Associated with the Throat Tuft Mutation (hfd) in the Japanese Quail

Hereditary abnormalities of head skeleton ascribed to embryonic visceral arch defects were investigated in Japanese quail homozygous for the throat tuft mutation (hfdTt). Differential staining for bone and cartilage of 15-day embryos revealed partial deletion or irregularity in the mandible, basiparasphenoid, hyoid apparatus, and quadratojugal bones, incidences of which were 84, 44, 40, and 18%, respectively. Incidence of the head-skeleton abnormality was 88% when individuals having at least one of the abnormalities mentioned were regarded as abnormal. Throat tuft (hfdTt) and ear tuft (hfd) homozygotes showed distinct differences between them, although both alleles are associated with visceral arch defects.