Date of Defense
4-27-2026
Date of Graduation
5-2026
Department
Biological Sciences
First Advisor
John Spitsbergen
Second Advisor
Giovanna Nolasco de Carvalho
Abstract
The neuromuscular junction (NMJ) is a synapse that helps maintain and coordinate communication between motor neurons and the skeletal muscle fibers. This connection enables muscle contraction. The unique structural organization of the NMJ includes the clustering of acetylcholine receptors (AChRs). These are essential for the transmission. Any changes in this structure, including the AChR clusters becoming fragmented have been linked to neuromuscular diseases and routine biological processes. However, less is known about how this fragmentation changes throughout early developmental stages. As well as how this could change or differ from muscle type, sex, and age. This study aimed to quantify endplate fragmentation in sedentary rats across the ages of 3, 5 and 8 weeks of age. This was calculated using the software ImageJ to gather fragmentation index numbers, a normalized measure of AChR clusters. Around 900 endplates were measured from all the groups and the fragmentation index was put into a three-way ANOVA statistical test. This was performed to compare the different groups and identify significant changes between them.
Results demonstrated a significant increase in the fragmentation index across all ages. This was present in both female and male as well as muscle types. This indicated that NMJ structure is undergoing continual remodeling during development. Additionally, fragmentation differed between the soleus (slow- twitch) and plantaris (fast-twitch) muscle groups. This suggested that different muscle demands could influence NMJ morphology. These findings support the hypothesis that NMJ doesn’t solely mark degeneration but also can reflect normal remodeling of the NMJ.
Overall, this study highlights how dynamic the NMJ structure is. This is changing in early developmental stages and can differ based on muscle demand. Understanding how these changes effect muscle communication can help future research regarding muscle use and function with neuromuscular diseases. This work was completed under Dr. John Spitsbergen and PhD candidate Allexia Galentine at Western Michigan University.
Recommended Citation
Martin, Drew, "Muscle-Specific Neuromuscular Endplate Fragmentation Index Changes" (2026). Honors Theses. 4041.
https://scholarworks.wmich.edu/honors_theses/4041
Access Setting
Honors Thesis-Restricted
Restricted to Campus until
6-8-2028