Abstract
Experiments were carried out to study the effects of a heterotopic limb upon the growth of the spinal nerves in the vicinity of the lumbosacral plexus and to analyze the muscular movements of the limbs.
The hind-limb rudiment of Amblystoma punctatum was excised at stages varying from 39 to 45 and implanted from one to 5 segments anterior to its normal position. Two types of operations were performed, an autoplastic series in which the right hind-limb rudiment was excised and reimplanted to the flank, and a homoplastic series in which either a right or a left hind-limb bud was transplanted to corresponding positions anterior to the normal limb.
The limb rudiments transplanted at stages 42 to 45 were given various orientations. It was found that both the antero-posterior axis and the dorsoventral axis are irreversibly fixed at stage 42.
When the wound made by the removal of the limb bud was covered with indifferent ectoderm from the flank region, regeneration occurred in only 9 out of 51 cases. When the wound was not cleaned or covered regeneration took place in 59 out of 96 cases.
The hind-limb is normally innervated by the ventral rami of the 15th, 16th, and 17th spinal nerves. Coordinate and homologous movements were observed in many grafted limbs which had been implanted from one to 3 segments anterior to their normal position. The type of function was similar to that reported by Weiss, 1 Detwiler, 2 and Detwiler and Carpenter. 3 The homologous muscle groups in the heterotopic limb, irrespective of limb orientation, flexed and extended synchronously with those of the ipselateral normal limb, and alternate with those of the contralateral limb. The grafted limbs in such cases were found to be innervated by one or more branches from the normal lumbosacral plexus.
Get full access to this article
View all access options for this article.