Microwave Irradiation as a Generator of Heat for Histological Fixation

Abstract

The kitchen appliance known as the “radar oven” generates heat quickly in materials containing water. Protoplasm exposed to the irradiation can thus be denatured. The amount of heat generated is a function of the time of exposure and the intensity of the irradiation, and the size and specific heat of the tissue or organism being irradiated. But docs such heating have applicabiity to histological technique? One of four carcas temperaturea (approximately 60°, 70°, 77°, and 85 C) was generated in anaesthetized, adult hairless mice of both sexes. “Control” animals were not irradiated. Specimens of liver, kidney, lung, and (from males) testis were taken from the five groups; the tissue spedmens were dehydrated in tetrahydrofuran, embedded in paraffin, sectioned at 9 μm, and stained with hematoxylin and eosin. The preparations were suitable for histological examination. Each organ had an optimum temperature for histological fixation under the conditions of this experiment: liver, ∼70°; kidney, ∼77°; lung, ∼77°; and testis, ∼85 C. Heat fixation by microwave irradiation also shows some applicability to electron microscopical studies and to investigations of the blood vascular arrangements of organs.