Journal of Neuroscience, Vol 8, 3094-3099, Copyright © 1988 by Society for Neuroscience
Topographically selective reinnervation of adult mammalian skeletal muscles
MB Laskowski and JR Sanes
Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110.
In 2 rat muscles, serratus anterior and the diaphragm, the rostrocaudal
axis of the motor pool is mapped onto the rostrocaudal axis of the muscle's
surface (Laskowski and Sanes, 1987a). One possible basis for this orderly
topography is that motor axons and intramuscular structures bear labels
that favor connectivity among positionally matched partners. To test for
the existence of such labels, we asked whether axons would selectively
reinnervate appropriate portions of the muscles following nerve
transection. We found that, on average, rostral and caudal halves of each
muscle were preferentially reinnervated by axons from the rostral and
caudal halves of its motor pool, respectively. In the serratus anterior,
reinnervation was more selective following denervation in neonates than
following denervation in adults, although in neither case was the normal
pattern of innervation reestablished completely. These results show that
motor axons can selectively reinnervate adult rat muscles, and support the
idea that positional cues play a role in organizing neuromuscular
topography.