The condition of phocomelia, a human birth defect in which the long bones are shorter than normal, is mimicked in developing chick limb buds exposed to X-rays. Studies of X-irradiation-induced phocomelia have served as evidence supporting the 'progress zone' model of limb patterning. Here, X-irradiation-induced phocomelia is shown not to be a patterning defect at all; rather, it results from a time-dependent loss of skeletal progenitors.
- Jenna L. Galloway
- Irene Delgado
- Clifford J. Tabin
