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Dissection of Single Skeletal Muscle Fibers for Immunofluorescent and Morphometric Analyses of Whole-Mount Neuromuscular Junctions
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Neuromuscular Junction Development Differs Between Extraocular and Skeletal Muscles and Between Different Extraocular
Sampath Vemula1,2,3, Tapiwa Muvavarirwa1,2,3, Fleur Doornbos1,2,3
1Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
Investigative Ophthalmology & Visual Science
|May 20, 2024
Summary
Neuromuscular junctions (NMJs) in extraocular muscles (EOMs) develop uniquely compared to other skeletal muscles, featuring distinct morphology and more subsynaptic nuclei, potentially aiding precise eye movement control.
Area of Science:
- Neuroscience
- Muscle Physiology
- Developmental Biology
Background:
- Neuromuscular junctions (NMJs) are critical for muscle function.
- Skeletal muscles exhibit diverse physiological properties.
- Extraocular muscles (EOMs) are responsible for precise eye movements.
Purpose of the Study:
- To investigate developmental differences in NMJs between EOMs and other skeletal muscles.
- To compare the morphological maturation of NMJs in EOMs versus limb and diaphragm muscles.
Main Methods:
- Collected mouse EOMs, diaphragm, and tibialis anterior (TA) at various postnatal ages.
- Stained whole muscles for NMJs, neurofilaments, and myosin heavy chains.
- Imaged and quantified NMJ morphology using confocal microscopy and Imaris software.
Main Results:
- EOM NMJs displayed unique developmental patterns, differing from diaphragm and TA.
- EOM NMJs were larger relative to myofiber size and possessed more subsynaptic nuclei.
- Specific EOMs (inferior oblique, inferior rectus) showed delayed NMJ development.
Conclusions:
- EOMs exhibit a distinct NMJ developmental trajectory compared to other skeletal muscles.
- The unique NMJ characteristics in EOMs may underlie the fine motor control of eye movements.
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