On the supposed pluri-segmented innervation of muscle fibres

Cattell and Stiles (1) have recently claimed to show that the majority of skeletal muscle fibres, at least in frogs, have a pluri-segmental innervation. The existence of a similar innervation in mammalian muscle fibres has also been asserted by Agdulhr (2). The evidence supporting this theory falls into two categories. The first is based on the histological findings after Wallerian degeneration has occurred in the axons rising from one spinal segment. In such cases muscle fibres were found in which one axon and motor end-plate showed signs of degeneration, and the other, when two were present, did not. Agduhr, who made the observation, concluded that the degenerated axon came from the segment whose motor roots he had cut 56 to 144 hours previously, and the undegenerated axon from another spinal segment. He was careful, however, to point out in his last paper that the total number of such doubly (or trebly) innervated fibres could not be adduced from his experiments.