An experimental study on the length change of the sarcomere in rat during the rigor mortis.

Objective The purpose of this study is to observe the length change of the rats sarcomere during the rigor mortis.Method Twenty one rats were divided into three groups and samples were taken immediately after death,2h,4h,6h,8h,12h,24h,postmortem(p.m.).The sarcomeres of 21 rats at various postmortem intervals were measured under the scanning electron microscope(SEM).Results Morphologically,the myofibrils of samples taken immediately after death were loose and separate each other.At 2h p.m.,the borders between the myofibrils were blurred and periodicalstriationsappeared.At 4h p.m.,and 6h p.m.,the striations of the muscles fibers became apparent.At 12h p.m.,myofibrils were broken,but striations still could been seen.At 24h p.m.myofibrils were broken and melted.Compared with the length of sarcomeres sampled immediately after death,the length of the myofibrils were significant short at 2?4?6?8h p.m.in three groups( P 0 001),but at 12h p.m.,there was no significant difference in three groups( P 0 05);At 24h p.m.there was no significant difference in the first and third group( P 0 05),while in the second group there was significant difference( P 0 01).Conclusion The length of the sarcomere was changing along with the time elapsed after death during the rigor mortis.