Regenerative response of amputated forelimbs of Xenopus laevis froglets to partial denervation

Xenopus laevis froglet forelimbs normally respond to amputational injury by forming a heteromorphic cartilaginous rod-shaped outgrowth. However, partial denervation of a forelimb by ablation of the N. radialis or the N. ulnaris, followed in 2 days by amputation through the mid radius-ulna, results in a size deficiency of the regenerative outgrowth 14 and 21 days postamputation. The decreasing quantity of forelimb innervation, as a result of partial denervation by 55 or 45%, apparently has a graded effect on the cell population and on the extent of cartilage development in the outgrowth. As a consequence of amputational injury, a nerve independent response of the periosteum was also found. This response produced considerable thickening in the periosteum and was due to cell proliferation in both the control and denervated cases.