MicroCT images of Xenopus frog forearm and spikes. A: An original microradiograph of an unoperated frog hand obtained by the microCT scanner with a setting of 45 kV, 80 μA. The white line indicates the future limb amputation site. B: An original microradiograph of a frog spike with a setting of 70 kV, 140 μA. The spike with skin was incubated in 50% Hexabrix for 1.5 hr before scanning. C: An original microradiograph of a frog spike with a setting of 85 kV, 160 μA. The spike was skinless and was incubated in 50% Hexabrix for 2 hr before CT scanning. D: A sagittal sectional view from the 3D reconstructed image of the spike in C. Spike tissue was distinguished by distinct gray value thresholds. For better image presentation, the voxels with gray values less than 32,075 were set as full transparent, 32,075–39,700 as bone, 39,700–46,600 as cartilage, and 46,600–59,960 as muscle. The white lines in B–D indicate the limb amputation plane. Image A–C are inverted using photoshop.