Effects of microwave irradiation and chemical fixation on the localizationof perisinusoidal cells in rat liver by gold impregnation

Modified gold impregnation is one of the methods that are used in light mic roscopical demonstration of hepatic perisinusoidal cells. This method has s ome disadvantages, such as restriction of fixation time to 16 h, which allo ws limited time for processing the tissues, especially when dealing with a large amount of material, and a long impregnation time (16-24 h). We invest igated the effect of prolonged fixation on the staining of sections, to sho rten the time needed for gold impregnation by using microwave irradiation. Liver specimens were fixed in Baker's calcium-formalin for different period s of time. After fixation, frozen sections were impregnated in gold chlorid e solution either at room temperature or in a microwave oven. The staining quality of the sections which had been impregnated in the microwave oven fo r a much shorter time were equal to or even superior to the ones impregnate d at room temperature. Prolonging the fixation time up to 7 days did not af fect the staining results by microwave irradiation, whereas satisfactory re sults were not obtained from sections stained at room temperature and fixed for more than 3 days. We conclude that microwave irradiation can be used t o shorten the impregnation time in gold chloride solution and the duration of fixation can be prolonged up to 3 days in the original method and up to 7 days when microwave irradiation is used during impregnation.