THE THICK TAIL MUTATION CONTAINS ANOMALIES OF THE AXIAL SKELETON

Analysis of the skeletal effects of thick tail (Tht), a radiation-indu ced mutation, has revealed numerous anomalies in the axial skeleton. T he affected regions include the atlantal-occipital region as well as t he lumbar (Lu) and caudal (Ca) vertebrae in which the ossified adult s tructures are either missing or reduced in size. Skeletons of juvenile Tht heterozygotes exhibit a malformed occipital bone, atlas, smaller Ca vertebrae, and delayed ossification of the affected adult structure s. The diminished amount of cartilage and bone suggests that the Tht g ene may be functioning during the formation of these tissues.