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Introduction of Periodic acid Schiff’s (PAS) Stain PAS stain is used for the demonstration of basal membrane, fungus, differentiate mucin secreting adenocarcinoma from undifferentiated squamous cell carcinoma. It is helpful in the diagnosis of different types of glycogen storage diseases, Paget’disease, macrophages in Whipples diseases, parasites, and amylase. Principle of PAS stain Structures having 1-2 glycol or amino or alkyl grouping are oxidized by periodic acid. Free hydroxyl groups must be present for oxidation. After complete...

Introduction of Gomori’s methenamine silver stain Gomori’s methenamine silver stain (GMS) is a Grocott’s modification that delineates fungal elements sharply in black against a pale green background. It is especially useful as a histopathological tool and for the detection of Pneumocystis jiroveci. Principle of Gomori’s methenamine silver stain The cellular walls of fungi are very thick and contain much more carbohydrates.  Chromic acid creates dialdehyde groups from the carbohydrates of the fungi cell walls with over oxidation and...

Introduction of DNA Microarray  Genes and their expression profiles were previously researched on a case-by-case basis. We can now look at numerous genes at once thanks to DNA microarray technology. It enables quantitative and qualitative comparisons of two cells' gene expression patterns. Definition of  DNA microarrays DNA chips are also referred to as arrays since they are arranged in a specific pattern. These chips are also known as gene chips and biochips. Each DNA fragment encoding...