The effects of microwave-irradiated fixation for postmortem changes of the kidney.

In the present study, we evaluated the advantages of microwave-irradiated fixation for postmortem autolysis of the kidney. Mouse kidneys, sampled at 0, 1, 3, 5, 10, 15, 20 and 25 hr after death, were fixed with 10% neutral formalin by microwave irradiation (MWI; 20 sec/500 W) and by conventional immersion. They were then examined with light and electron microscopy, morphometrics and immunohistochemicals. Light microscopic and morphometric observations showed that structural preservation effect of MWI was limited to the proximal convoluted tubules at 25 hr. Contrary, mild ultrastructural damage by MWI was found in the glomeruli at 0 and 15 hr. Immunohistochemistry for renin and α-smooth muscle actin showed no apparent differences between MWI and the immersion.