Myonuclear addition to uninjured laryngeal myofibers in adult rabbits.

Objectives: In normal mature limb skeletal muscle, satellite cells are quiescent and myonuclei do not divide after formation of their associated myofibers in the absence of injury. The possibility of myonuclear addition in uninjured laryngeal myofibers of adult rabbits was investigated in an immunohistochemical pilot study. Methods: Bromodeoxyuridine (brdU), a marker for cell division, was administered by intraperitoneal injection over a 12-hour period in rabbits. The number of brdU-positive myonuclei per myofiber was determined on cross sections through the thyroarytenoid (TA) and posterior cricoarytenoid (PCA) muscles. Results: In the TA muscle, 0.13% +/- 0.03% (mean +/- SEM) of the myofibers counted had a brdU-positive nucleus. In the PCA muscle, 0.13% 0.01 % of the myofibers counted had a brdU-positive nucleus. Approximately 0.2% and 0.3% of the myofibers of the TA and PCA muscles, respectively, had brdU-positive satellite cells associated with them. Tibialis anterior and pectoralis major muscle controls were negative for brdU-positive myonuclei. Conclusions: These data support the possibility of continuous remodeling in uninjured adult laryngeal myofibers and accentuate the distinct nature of laryngeal muscle relative to limb skeletal muscle in the rabbit model.