Cell death in the regressing claws of
. TUNEL stainining for apoptotic cells, which appear black, at stage 36 of development. (A) In the clawed pedal digit III apoptotic cells are associated only with the overlying surface epithelium. In the unclawed pedal digit II, (B,
C) positively-reacting cells are located in the developing claw and in the overlying epithelium (arrow in B). (D) A higher power view of the region depicted in panel (C) shows positively reacting cells in both the claw sheath and the underlying ungual phalanx (arrows). Scale bars, 100 μm.