Golgi Tendon Organ Development and Contracture Formation Following Neonatal Brachial Plexus Injury Open Access Deposited
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Date Modified: 05/17/2017
Neonatal Brachial Plexus Injury (NBPI) is a common birth injury to the nerves innervating the upper limb. A poorly understood and currently incurable consequence of this injury is tightness of affected muscles, or muscle contractures. Paradoxically, contractures do not occur in a rare form of NBPI (preganglionic) in which afferent (sensory) innervation of the muscle is preserved, in contrast to the more common postganglionic NBPI which causes complete denervation, suggesting a possible role of afferent denervation in contracture formation. Afferent neurons interface with muscle at the spindle and golgi tendon organ (GTO). Previous studies have implicated muscle spindles in contracture formation, but the GTO has not been investigated. Unilateral pre and post-ganglionic NBPIs were created in neonatal mice. Bilateral biceps muscles were harvested four weeks later, cleared, and immunohistochemically stained in whole mounts to assess GTO morphology. The nerves innervating the biceps were sectioned and stained to quantify afferent denervation. Complete denervation by postganglionic NBPI led to loss of GTO in denervated muscles, whereas preservation of afferent innervation in preganglionic NBPI preserved normal GTO morphology. These findings suggest that afferent innervation is required for postnatal GTO maintenance, and that loss of the GTO may play a role in contracture formation.
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