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Morphological changes of rats muscles at various postmortem intervals by scanning electron microscopy
1Faculty of Forensic Medicine, West China University of Medical Sciences, Chengdu 610041.
Abstract:
The aim of this study was to observe the morphological changes of muscle in the process of rigor mortis. The quadriceps of 40 rats at various postmortem intervals were observed under the scanning electron microscope (SEM) and the light microscope by phosphotungstic acid-haematoxylin (PTAH) stain. The results showed that the striations of muscle were blurred within 4 h, but they became apparent from 6 h to 24 h after death. The authors suggest that this phenomenon be associated with the increased resistance of muscle against the postmortal changes. The observations by scanning electron microscopy and light microscopy have revealed that the muscles do contract in the process of rigor mortis because the distance between two Z lines shortens and the 1 band narrows, compared with those in anaesthetised animals. The basic biochemical process for the formation of rigor mortis is the same as that of muscle contraction except that the former happens postmortem and the latter antemortem.
Insights
Rigor mortis causes muscle contraction, evidenced by observable changes in muscle striations and Z-lines. This postmortem muscle stiffening shares biochemical processes with antemortem muscle contraction.
Area of Science:
- Muscle Physiology
- Postmortem Biology
Background:
- Rigor mortis is a well-known postmortem phenomenon characterized by muscle stiffening.
- Understanding the precise morphological changes during rigor mortis is crucial for forensic science and pathology.
Purpose of the Study:
- To investigate the morphological alterations in skeletal muscle during the progression of rigor mortis.
- To compare postmortem muscle changes with antemortem muscle contraction.
Main Methods:
- Utilized scanning electron microscopy (SEM) and light microscopy with phosphotungstic acid-haematoxylin (PTAH) staining.
- Examined quadriceps femoris muscles from 40 rats at various postmortem intervals.
Main Results:
- Muscle striations initially blurred within 4 hours postmortem, becoming distinct between 6 and 24 hours.
- SEM and light microscopy revealed muscle contraction during rigor mortis, indicated by shortened Z-lines and narrowed I-bands.
- These changes were compared to muscle morphology in anesthetized animals.
Conclusions:
- The observed morphological changes suggest increased muscle resistance to postmortem degradation.
- The fundamental biochemical mechanisms of rigor mortis are analogous to antemortem muscle contraction, differing primarily in their timing (postmortem vs. antemortem).
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