Evidence of programmed cell death during the early stages of the development of unclawed manual digits of
. (A) Dorsal view of the entire left manus in the early part of stage 35 of development, a time at which all digits appear identical. (B,B’,C,C’) Details of the tip of manual digits II and III in the early part of stage 35 of development. DAPI staining (B,C) and activated caspase-3 staining (red spots) (B’,C’) show no evidence of apoptosis in the clawed digit (B’), but concentration of apoptotic activity in the mesenchyme underlying the surface epithelium at the tip of the unclawed digit (C’) (arrows). Scale bar 1 mm for (A) and 100 μm for (B,B’,C,C’).