This study compares microwave fixation of whole fetal specimens with conventional techniques performed at room temperature. All fetuses were obtained from the same pregnant rat; half of them were placed in neutral formalin for 15 min at room temperature, then irradiated for 2.5 min in a domestic microwave oven. The remaining fetuses were placed in neutral formalin at room temperature for 48 hr as a control. Both experimental and control groups were exposed to routine tissue processing for light microscopy and embedded in paraffin wax. Sections 5 microns thick were stained with hematoxylin and eosin. Our results showed that the microwave technique reduced the fixation time while providing thin sections that were equal to or better in quality than those in the control group.

The microwave oven has many potential applications, ranging from tissue fixation to staining for light and electron microscopy. This study was planned to speed up the staining of ultrathin sections. The first set of grids was stained conventionally with uranyl acetate and Reynold's lead citrate solutions. The other grids were stained with the same solutions by microwave irradiation. The electron micrographs of grids stained using the microwave technique were as satisfactory as the grids stained conventionally. Microwave-treated grids demonstrated more uniform staining and less precipitate. The use of a microwave oven shortened staining time by approximately 38 min.

Conventional methods for histological preparation of degenerated myelin are time-consuming and difficult. The purpose of our study was to shorten the time required for the procedure and to obtain better quality results for light microscopic demonstration of degenerated myelin in the central and peripheral nervous systems by using microwave irradiation. Rat brain and sciatic nerve were used for the study. The middle cerebral artery was occluded and the sciatic nerve was cut to produce myelin degeneration. Marchi's method was used for staining degenerated myelin. Fixation for light microscopy that would take two days using the conventional procedure was completed in 16.5-18.5 min using microwave irradiation. While staining of degenerated myelin requires 10 days for the conventional Marchi method, we decreased it to 7 h for brain tissue and 1 h for sciatic nerve by using the microwave oven. Moreover, a better quality preparation was achieved in the groups stained under microwave irradiation than those prepared by the conventional method.