Periodic Acid Schiff Reactions and General Tissue Morphology of Conventionally-processed versus Two Rapid Microwave-processed Tissues

Aims: To utilise the laboratory microwave as an instrument for a faster, cheaper and reliable tissue processing in the paraffin technique, to establish a processing schedule that eliminates xylene and replace it with a suitable alternative. To check the effect of microwave processing techniques on glycogen reactions as well as tissue morphology.

Study Design: Animal acquisition, sacrifice, harvesting and fixation of tissues. Grossing into triplicates, processing using three different techniques namely the conventional paraffin wax method, the microwave without vacuum method and the microwave with vacuum method. Staining using the PAS-Diastase as well as Haematoxylin and eosin staining techniques. Assessment and grading of morphology and staining characteristics.

Place and Duration of Study: Apparently healthy rabbits from the animal house, National Veterinary research Institute, Vom, Jos, Nigeria, between August and December, 2014.

Methodology: Two apparently healthy rabbits were sacrificed. The lungs, heart, liver, kidney, stomach, and spleen of each were harvested and fixed in 10% buffered formalin for three days. They were grossed into triplicates, labeled and processed using the conventional, microwave without vacuum and microwave with vacuum respectively. They were sectioned and stained simultaneously using the PAS-Diastase as well as H & E staining techniques. They were graded as excellent if they permitted microscopy, fair if not very good but can permit microscopy and poor if they cannot permit microscopy at all. Statistical data generated were processed using one way analysis of variance (ANOVA) at 95% confidence interval.

Results: Processing cycle as well as quantity of reagent used per cycle is greatly reduced in the microwave techniques. Tissue morphology, special features as well as glycogen were clearly demonstrated without significant differences. Dye uptake as well as section thickness were comparable among the three techniques. Block durability is comparable among the three techniques after 64 weeks of storage. There was no statistically significant difference in details of microscopic assessment/quality of tissue preservation (P=.90) and details of microscopic assessment/quality of staining (P=.74).

Conclusion: Same-day turn-around is possible in histology, with reduced reagent consumption and elimination of xylene, without compromising section quality, dye uptake or the reactions of glycogen in the PAS-Diastase technique. This will result to quick diagnosis hence quick intervention at a cheaper rate to both laboratories and clients. It is a good innovation in forensic and diagnostic histopathology and should be encouraged. Its compatibility with other histochemical techniques, immunohistochemical and molecular techniques should be evaluated to give a wider application.