Fig. 2. Pattern of cell death and affected tissue layer in ozd limbs. (A-D) TUNEL analysis of sectioned, st. 24 wild-type and ozd limb buds reveals an abnormal pattern of cell death in ozd. Beneath each section is a picture of the limb bud prior to embedding, shown to better understand its shape. Arrows in B and D indicate the lack of cell death along the posterior border. (E) Normal skeletal pattern of a recombinant limb constructed with wild-type ectoderm and mesoderm. (F) Recombined ozd ectoderm and wild-type mesoderm result in a normal skeletal pattern. (G) Recombined ozd mesoderm and wild-type ectoderm produce wings with an ozd skeletal pattern. Axial orientations are indicated in A. A, anterior; Di, distal; P, posterior; Pr, proximal.