Figure 1. The tiny limb grows at an increased rate compared to an unamputated limb.

(A) Time course of growth in amputated (top panel) and the contralateral non-amputated (lower panel) limbs on a 10 cm animal over 146 days. (B) The ratio of limb to body length in regenerating and unamputated limbs was measured over time (10 cm animals; n = 10). We have separated the growth of the limb regenerate into three stages: the blastema stage (dark gray), the early tiny limb stage (medium gray), and the late tiny limb stage (light gray). Error bars = standard deviation. t-Test was used to evaluate significance between the regenerating and uninjured limb size at each time point. All data points not marked with N.S. had p-values less than 0.005. (C) Histogram showing the average amount of time in days that the regenerating limb is in each growth stage for animals of different sizes (4, 10, and 20 cm in length).

Figure 1—figure supplement 1. Axolotl size measurements.

Body length is measured from snout to tail tip. Limb length is measured by measuring from the limb/trunk junction to the elbow (A) and then from the elbow to the tip of the longest digit (B). All measurements are recorded in centimeter (cm).

Figure 1—figure supplement 2. Animal size corresponds with growth rate during limb regeneration.

(A) Limb growth rates over the first 7 days of each growth phase were quantified using limb length measurements on unamputated limbs, early tiny limbs, late tiny limbs, and fully regenerated limbs of 4 cm (n = 20), 10 cm (n = 10), and 20 cm animals (n = 10). The body length represents their size at the time of amputation. Error bars = SEM. p-Values calculated by ANOVA and the Tukey post hoc test. * = p < 0.05 ** = p < 0.005. (B) Body length measurements of 4 cm (n = 20), 10 cm (n = 10), and 20 cm animals (n = 10) over time. Error bars = standard deviation. The body length represents their size at the time of amputation.