Fig. 3

Aborted limb stumps exhibit persistent collagen deposition. A Masson’s trichrome stain was performed on limbs that failed to regenerate (“stumps”) following repeated amputation and on intact control limbs. a Column a (leftmost) depicts an intact specimen (no amputations). b Column b (middle) depicts a specimen following same-plane, repeated amputation. c Column c (right) depicts a specimen following serial-plane, repeated amputation. Top panels show representative images of intact control a and failed regenerates from limbs amputated in the same plane b and limbs amputated serially distally c. Middle and lower horizontal panels are higher magnification views of images in the top panels. Brackets delineate epidermis, arrowheads indicate substratum compactum (dermis), double arrowheads indicate connection between substratum compactum and epidermis, and arrows indicate epidermal tongues. Scale bars in top rows are 500 µm, and scale bars in middle and bottom rows are 100 µm