Assessment of the Conventional versus Two Rapid Microwave Processing Methods Using the Phosphotungstic Acid Haematoxylin Technique

Aims: To process tissues using the rapid microwave techniques and check their reactivity with the phosphotungstic acid haematoxylin. To establish a very fast and cheap method of tissue processing and evaluate its effects on tissue morphology and dye uptake. To eliminate xylene from the processing schedule. To check for additional information that can be obtained from the phosphotungstic acid haematoxylin technique so as to encourage its use in the laboratory.

Study Design: Harvesting and fixation of tissues. Grossing into triplicates, processing using three different techniques. Staining and grading of sections.

Place and Duration of Study: Human samples were obtained from the Anatomy Department, Nnamdi Azikiwe University, Nnewi Campus while animal samples were obtained from the Animal experimental station, National veterinary Research institute, Vom, Nigeria. The work was done between August and December, 2014.

Methodology: Heart, skin, brain, kidney, lungs, and liver tissues were harvested from an apparently healthy rabbit after sacrificing it scientifically. Ethical clearance as well as human cervix, fibroid, prostate and testis were obtained. All samples were fixed in 10% buffered formalin, cut into triplicates and processed using the conventional as well as two rapid microwave techniques respectively. Sections were made from each technique and stained simultaneously using the Phosphotungstic Acid Haematoxylin technique. The Masson Trichrome methos as well as the Haematoxylin and Eosin Techniques were also used to assess morphology They were each evaluated for quality of block, ribboning, nuclear, cytoplasmic and extracellular components, collagen and muscle fibre. Section thickness, uniformity and staining intensities were all checked.

Results: Processing cycle as well as quantity of reagents used was drastically reduced in the microwave techniques. Paraffin blocks obtained, ribbonning as well as flattening on 20% alcohol were comparable in the three techniques. Tissue morphology, integrity of tissue as well as tissue histochemistry to the phosphotungstic acid haematoxylin were comparable among the three techniques. The stroma of the cervix is better retained in the microwave with vacuum technique.

Conclusion: Samples received in histology laboratory can be processed and slides produced within the same day without compromising tissue morphology or histochemistry. Xylene can be eliminated from the paraffin wax processing cycle with quality paraffin block and ribbon production. The cost and duration of tissue processing can be drastically reduced with the production of quality sections. This work can be replicated using other histochemical techniques to give a wider application.