Structural changes developing with rigor that facilitate bacterial invasion of muscle tissue

Area of Science:

• Muscle physiology
• Microbiology

Background:

• Muscle fibers exhibit volume changes in response to osmotic conditions before rigor mortis.
• The structural integrity of muscle tissue post-rigor is not fully understood.

Purpose of the Study:

• To investigate the dimensional changes of skeletal muscle fibers during rigor mortis.
• To elucidate the mechanism of bacterial penetration into muscle tissue.

Main Methods:

• Comparative analysis of pre-rigor and post-rigor muscle fiber dimensions.
• Exposure of muscle fibers to hypertonic and hypotonic fixative solutions.
• Microscopic examination to identify bacterial entry points.

Main Results:

• Pre-rigor muscle fibers showed radial shrinkage in hypertonic solutions and swelling in hypotonic solutions.
• Post-rigor muscle fiber radial dimensions remained constant across varying fixative osmolalities.
• Rigor development causes muscle fibers to shrink radially, potentially detaching from surrounding endomysia.
• Gaps formed between post-rigor fibers and endomysia were observed to contain muscle cytoplasm.
• These gaps serve as pathways for bacterial penetration into muscle tissue.

Conclusions:

• Skeletal muscle undergoes significant radial shrinkage during rigor mortis.
• This shrinkage creates anatomical gaps facilitating bacterial invasion of muscle tissue.
• Understanding these structural changes is crucial for food safety and understanding post-mortem spoilage.