Fig. 6

Repeated amputation has systemic effects on digit tip regeneration. A Experimental outline of experiment 4 (see “Methods” for description). B–D Quantification of normalized bone volume (B), bone length (C) and rate of volume change (D) for digits amputated 5 times (5th Amp; n = 32–52 digits) and middle digits amputated for the first time, where the 2nd and 4th hindlimb digits went through 4 amputation–regeneration cycles but were not amputated for a 5th time. (1st Amp MD; n = 20 digits). Data are presented as mean ± SD and differences were determined using an unpaired t test. * = p < 0.05; ** = p < 0.01; *** = p < 0.001; **** = p < 0.0001. Black dashed lines indicate when digit tip amputation occurred