Various experiments were performed on the limb buds of axolotls to compare the behaviour of amphibian limbs with that previously reported for chick limbs. Following removal of the tip or whole limb bud, extensive powers of regulation were observed since complete limbs always formed. Similarly after distal to proximal grafts intercalary regulation occurred to produce perfect limbs and after prox...

A standard set of six experiments performed on the limb buds of two species of Anurans - Rana temporaria and Xenopus laevis - are described. The experiments are limb-bud amputation, distal to proximal shifts, proximal to distal shifts, inversion of the dorsoventral axis inversion of the anteroposterior axis and inversion of both axes. The results are compared to those previously reported for Ur...

Could it be possible that, in the not-so-distant future, we will be able to reshape the human body so as to have extra limbs? A third arm helping us out with the weekly shopping in the local grocery store, or an extra artificial limb assisting a paralysed person? Here we report a perceptual illusion in which a rubber right hand, placed beside the real hand in full view of the participant, is pe...

Tail skin cuffs have been grafted to the upper forelimb of red-backed salamanders in either normal or 180°-rotated dorsoventral orientation. Subsequent amputation through the graft region resulted in arrested regeneration, distally deficient or typical four-digit regenerates. Distribution was not substantially influenced by graft orientation nor were there any supernumerary limbs induced by the...

Development of the mouse forelimb bud depends on normal Twist1 activity. Global loss of Twist1 function before limb bud formation stops limb development and loss of Twist1 throughout the mesenchyme after limb bud initiation leads to polydactyly, the ulnarization or loss of the radius and malformations and reductions of the shoulder girdle. Here we show that conditional deletion of Twist1 by Mes...

Tail skin cuffs have been grafted to the upper forelimb of red-backed salamanders in either normal or 180 degrees-rotated dorsoventral orientation. Subsequent amputation through the graft region resulted in arrested regeneration, distally deficient or typical four-digit regenerates. Distribution was not substantially influenced by graft orientation nor were there any supernumerary limbs induced...

Summary Changes in appendage structure underlie key transitions vertebrate evolution. Addition of skeletal elements along the proximal-distal axis facilitated critical transformations, including fin-to-limb transition that permitted generation diverse modes locomotion. Here, we identify zebrafish mutants form supernumerary long bones their pectoral fins. These new integrate into muscul...

Overhead manipulation tasks often require collaborations between two operators, which becomes challenging in confined spaces such as a compartment. Supernumerary Robotic Limb (SuperLimb), promising wearable robotic solution, can provide assistance terms of broader workspace, wider functionalities and safer working conditions. However, the safety concerns human-centered SuperLimb interaction mec...