Electron Microscopic Study of Freshly Fixed and Time-Delay Fixed Tissues in Rat

In a pathology laboratory, many tissues which are submitted or made available for electron microscopic study are obtained from autopsy. Morphological changes due to postmortem delay which may not be visualized when studied with a light microscope are readily seen with the electron microscope. Because of this, it is important to make a comparative study of the freshly fixed and time-delay fixed tissues assimilating those obtained at autopsy. This work presents the results of morphological changes in the brain, heart, kidney, liver, and striated skeletal muscle of the rat with a postmortem time-delay of 24 hours. In the case of striated muscle the time delay was up to 48 hours before fixation.Methods and Materials A 62 day old male rat of the Sprague Dawley strain, weighing 410 grams was used in this experiment. The rat was anesthetized with nembutal and quickly opened. The brain, heart, liver, kidney, and a small piece of femoral muscle were quickly removed.