Fig. 1

Development of the forelimb and hindlimb buds in emu embryos (staged by hindlimb and head characters). The hindlimb bud appears prior to the forelimb bud. Outgrowth of the forelimb bud is both delayed and retarded. The forelimb bud appears at HH stage 19 (see insert), when outgrowth of the hindlimb bud is already advanced. By stage 26, the hindlimb bud is significantly larger than the forelimb bud. By stage 33, the forelimb bud appears thin and elongated, with a single developing digit. The hindlimb buds are greatly elongated as they differentiate into legs and feet. Forelimb bud denoted by arrows. Hindlimb bud denoted by arrowheads. Bar 1 mm