Periodic Acid Schiff or PAS Staining: A Method to Assess the Structural Deformities of Glomerulus

The glomerulus is a complex network of capillaries within the kidney that filters waste and removes extra fluid from the blood. The renal filtration rate is dependent on this specialized structure, which can be examined using Periodic Acid Schiff or PAS stain.

To begin, take a paraffinized kidney cortex section on a glass slide. Treat the slide with xylene. Xylene molecules dissolve the paraffin wax from the tissue section. Next, expose the specimen to decreasing concentrations of alcohol. Alcohol removes traces of xylene while rehydrating the tissue section for subsequent binding of the stain.

Now, add periodic acid to the specimen. Periodic acid converts the diols present in the tissue polysaccharides, such as glycogen or mucin, to aldehydes. These aldehydes react with the Schiff's reagent, a fuchsin-sulfurous acid combination, forming a magenta-colored dye that stains the tissue section. Rinse the slide to remove excess stain.

Post rinse, add iron-hematoxylin, a nuclear counterstain that binds to DNA and stains it purple. Wash to remove excess stain. Finally, dehydrate the specimen with increasing strengths of alcohol followed by xylene, which serves as a clearing agent. This step helps improve the contrast of the tissue section for microscopic examination.

Glomerular disease can be visualized as thickening of the basement membrane, altered capillaries, and abnormal cells that relate to impaired renal function.

For detailed visualization of the glomerular cells and mesangial matrix, dry the fixed paraffin-embedded kidney cortex samples at 37 degrees Celsius for 1 hour, followed by deparaffinization with consecutive xylene and descending ethanol immersions. Rehydrate the samples in distilled water for 5 minutes and incubate the slides in Periodic Acid solution in a fume cabinet.

After 5 minutes, rinse the slides with three 5-minute washes in 100 milliliters of distilled water, followed by a 15-minute incubation in Schiff's reagent. At the end of the incubation, wash the slides in running tap water for 5 minutes and counterstain with hematoxylin for 3 seconds before thoroughly rinsing in running tap water for another 15 minutes.

Then, dehydrate the slides with ascending ethanol immersions and two consecutive 3-minute xylene immersions. After air drying, the slides can be mounted with xylene based mounting medium for assessment of their glomerular structure on a light microscope at a 400X magnification.

• Periodic Acid Schiff Stain - Method used to visualize glomerular cells and the mesangial matrix.
• PAS Stain Glomerulus - Specific application of PAS stain in kidney cortex study.
• Acid Schiff Staining - Another name for the PAS staining process.
• Periodic Acid Structure - Part of PAS stain, involved in revealing cellular structure in staining.
• Glomerular Tuft - Structure in kidney cortex, analyzed using PAS stain.

• Periodic Acid Schiff Stain - Define and contextualize (e.g., periodic acid schiff stain).
• Key Concepts - Summarize principles (e.g., staining theory).
• Underlying Mechanisms - Short description of PAS staining process.
• Connect to Experiment - Brief rationale linking periodic acid and schiff reagent to kidney cortex sample study.

• What is the Periodic Acid Schiff Stain method and how it contributes to kidney cortex research?
• How does the PAS staining process work?
• What is the role of the Glomerular Tuft in PAS staining?

• Describe Practical Applications - PAS stain used for analyzing kidney structures (e.g., medical diagnosis).
• Industry Impact - Benefits healthcare, particularly nephrology.
• Societal Importance - Enables better understanding of kidney diseases (e.g., education).
• Link to Scientific Advancements - Short description of innovations in staining techniques.