Ultrastructural analysis of mitochondrial morphology and in the human rhabdosphincter: Insights into urinary incontinence

Urinary incontinence increases with age, reducing the elderly quality of life. Understanding its mechanisms and developing treatments are urgent tasks. While healthy striated muscle maintains homeostasis through mitophagy, aging is thought to reduce autophagy activity. This study aimed to detect abnormal mitochondrial accumulation in the rhabdosphincter using transmission electron microscopy (TEM). We collected the rhabdosphincter samples from seven patients undergoing cystectomy and used the rectus abdominis as controls. Both tissues were examined with Hematoxylin and eosin (HE) staining and TEM. ImageJ software was used to measure the mitochondrial area, perimeter, and luminance. HE staining revealed that the rhabdosphincter had fewer muscle fibers and more stromal tissue than the rectus abdominis. TEM images showed more gaps in muscle bundles and signs of mitochondrial damage, vacuolation, and swelling in the rhabdosphincter. Quantitative analysis revealed a larger average mitochondrial area (0.21 μm² vs. 0.063 μm², p < 0.01), longer perimeter (1.83 μm vs. 0.94 μm, p < 0.01) and higher luminance (156.6 vs. 90.2, p < 0.01) than those of the rectus abdominis. The rhabdosphincter of elderly individuals showed significant mitochondrial morphological abnormalities, with increased swelling and vacuolation.