The innervation of supernumerary and replacing grafts of limbs in Eleutherodactylus martinicensis Available to Purchase

The innervation of grafted limbs in Eleutherodactylus martinicensis has been studied, mainly in comparison of supernumerary grafts with those which replace a host limb.

If batches of each type are fixed at different times after operation, it is found that the extent to which motor nerves penetrate into the grafts decreases with time after operation with supernumerary grafts, but not with replacing grafts.

The muscles of supernumerary grafts are innervated from collateral branches of axons, usually from among those which supply the normal limb. It thus seems that these collaterals which develop as far as the formation of functional nerve-muscle junctions become unstable in late stages of embryonic life.

In general, grafted fore limbs become functional much more readily than do hind limbs. The degeneration of the nerves to supernumerary fore limbs may be followed in the living animal by the loss of movement in the graft. Their loss of function is more marked when grafted heterotopically than when near the orthotopic position.

Histological evidence for the breakdown of the nerves to supernumerary grafts is presented, both in respect to fibres and the Schwann cells. A nerve to a graft degenerates more readily when it belongs outside the brachial or lumbar series.

Degeneration of nerves and loss of function of the graft proceeds more drastically with supernumerary homografts than with the corresponding autografts. In supernumerary autografts in which motor nerves have degenerated, cutaneous branches may extend further into the graft.

The breakdown of nerves is retarded in embryos kept at sub-normal temperatures.