Frequency of satellite cells in perisynaptic versus extrasynaptic regions of the rat soleus muscle

ABSTRACT

Whether satellite cell nuclei are more common in the vicinity of motor endplates than in extrasynaptic regions of rat muscle is not clear. If this were true, then perisynaptic satellite cells could play a role in the preservation of the endplate. We compared the frequency of satellite cell nuclei in the perisynaptic and extrasynaptic regions of rat soleus muscle. An absolute as well as a relative increase of perisynaptic satellite cells was found. The mean frequency of satellite cell nuclei per sarcomere was 0.016 in perisynaptic regions and 0.002 in extrasynaptic regions [P=0.01]. Also, perisynaptic satellite cells had many processes, and some features suggested a more active state. It was suggested that satellite cells might add to the pool of junctional myonuclei which synthesize acetylcholine receptor molecules, or help in the repair of the postsynaptic membrane. Alternatively, they may synthesize basal lamina components which are specific for the endplate