CELLULAR PATHOLOGY- Staining protocols - Essay Example

(McGavin and Zachary 2006). Fig1: Periodic acid Schiff stain (PAS) of kidney. (McGavin and Zachary 2006). PAS staining is based on the monosaccharide present in the compounds. In the PAS reaction, the glycogen is digested using the diastase enzyme. The deposited glycogen is then treated with PAS. PAS breaks the 1, 2 – glycol linkages yielding aldehydes. The presence of glycol is identified by the Schiff’s reagent. After the treatment, when viewed under the microscope, glycogen will appear as vacuoles present in the cytoplasm of the cell.

The glycogen molecule has irregular shapes with distinct nucleus. (McGavin and Zachary 2006). Glycogen storage diseases are easily identified by performing biopsy of a portion of the liver. Fig 2: PAS staining of the liver cells showing the hepatocytes filled with glycogen. (Schiff, Maddrey, and Sorrell, 2011). The second figure shows the PAS with diastase digestion. It is observed that the cells have clear vesiculated cytoplasm. Basement membrane: Basement membranes are the extracellular protein matrix with support tissues.

The basement membrane cells have epithelial and muscle cells. Basement membrane helps to bind the epithelia tissue to the supporting tissue and also a metabolic support. Epithelial cells growth and differentiation is controlled by the basement membranes. . Basement membrane contains the structural glycoprotein, fibrous proteins and glucosaminoglycan. PAS binds to the proteoglycans in the basement membrane. It also has the great affinity for the carbohydrate molecule. (Young et al. 2006). The abnormal thickening of the basement membrane is easily identified using the PAS staining.

Necrotizing glomerulonephritis may rupture the basement membrane partly or completely. Mesangial cellularity, increase in mesangial matrix material, mesengial interposition, sub endothelial capillary basement membrane thickening are evaluated best using the PAS staining technique. PAS – positive borders are identified by the increased number of lysosomes and lipid droplets, and a larger vacuole for hypokalemia. PAS positive brush border will be seen for the proximal epithelium if the nephrons are normal.

(Schrier 2007). Larger molecular immune complexes are seen using the PAS staining. Fig 3: Basement membrane stained with PAS. (Lerma and Rosner, 2013). This figure shows the positive results for PAS immunoglobulin. Mucin: Mucin glycoprotein plays an important role in protecting the intestine from the chemical and physical injuries. They are among the important protecting mechanisms. Mucins are large molecular weight proteins present in the intestines. Mucin contains a central protein covered with polysachharides.

About 60% of Mucin is composed of polysaccharides. Serine and threonine are the major amino acid in the protein. The protein core of Mucin does not play a major role in the special staining techniques but the carbohydrates play an important role in the analysis of Mucin. The protection of intestine is performed by Mucin in four ways: The rate of secretion of mucin, the ability to form a viscous layer,