Histopathologic evaluation of the effect of microwave irradiation on fixation of kidney tissue

Post-mortem structural changes in tissues cause technical difficulties in accurate histo-pathologic interpretation. In the present study, we evaluated the effects of microwave irradiation before tissue fixation on preventing post mortem autolysis and accelerating the process of tissue fixation in the kidneys. Twenty-four chickens randomly were divided into 8 groups of 3 each. They were slaughtered and stored at room temperature. At 0, 1, 3, 5, 10, 15, 20 and 25 hours the kidneys were removed from chickens. The right kidneys were used as controls and fixed by conventional method through immersing in 10% buffered formalin; all the left kidneys were first irradiated by microwave [MWI; 30sec/450 watt] and then immersed in 10% buffered formalin. Kidney tissue samples were prepared according to standard routines, sliced into sections measuring 5 microns and stained by hematoxylin and eosin; next, these slides were examined through a light microscope. Morphologic study showed no difference in tissue preservation between the two methods till 20 hours post-mortem; however, at 25 hours, samples that had been fixed according to the standard methods revealed marked post-mortem structural degeneration while samples receiving microwave irradiation before fixation had preserved their original structure to a greater degree. Microwave irradiation before fixation of kidney tissue that has been dead for up to 25 hours results in greater structural preservation as compared to fixation by routine methods. We recommend further studies, preferably by using image analyzing, immunohistopathology and electronic microscopy to scrutinize minute structural changes in detail