A Novel Type of Multiterminal Motor Endplate in Human Extraocular Muscles

作者：Liu Jing Xia; Domellof Fatima Pedrosa^*

来源：Investigative Ophthalmology & Visual Science, 2018, 59(1): 539-548.

DOI：10.1167/iovs.17-22554

• extraocular muscles
• motor endplate
• multiterminal motor endplate
• en grappe
• en plaque
• polyneuronal innervation
• myosin heavy chain
• acetylcholine receptor subunit

PURPOSE. To investigate the relation between type of motor endplate, acetyleholine receptor (AChR) subunit composition, and fiber types in human extraocular muscles (EOMs).
METHODS. EOM samples collected from subjects aged 34 to 82 years were serially sectioned and processed for inmmunohistochemistry, with specific antibodies against different myosin heavy chain (MyHC) isoforms, neurofilament, synaptophysin, and adult epsilon (epsilon) and fetal gamma (gamma) AChR subunits as well as alpha-bungarotoxin.
RESULTS. A novel type of motor endplate consisting of large, multiterminal en plaque endings was found in human EOMs, in addition to the previously well-described single en plaque and multiple en grappe endplates. Such novel endplates were abundant but exclusively observed in myofibers lacking MyHC slow and fast Ila but containing MyHC extraocular (MyHCeom), isoforms. Multiple en grappe endings were found only in myofibers containing MyHC slowtonic isoform and contained fetal gamma AChR subunit. Adult a and fetal gamma AChR subunits, alone or combined, were found in the multiterminal endplates. Distinct AChR subunits were present in adjacent motor endplates of a given myofiber containing MyHCeom.
CONCLUSIONS. Human EOMs have a more complex innervation pattern than previously described, comprising also a novel type of multiterminal motor endplate present in myofibers containing MyHCeom. The heterogeneity in AChR subunit composition in a given myofiber suggests the possible presence of polyneuronal innervation in human EOMs.

• 出版日期2018-1