Carbohydrates and Amyloids Histotechnology

Glycogen deposition sites & significance

Found in liver, hair follicles, endometrial glands, vaginal epithelium, and cardiac/skeletal muscles; significant for tumors and carbohydrate enzyme metabolism deficiencies.

Mucins classification & origins

Polypeptides secreted by epithelial and connective tissue cells, divided into neutral and acidic mucins based on origin/structure; produced by tumors and enzyme deficiencies.

Amyloid deposition sites

Intercellular material deposited in muscles, heart, skin, liver, spleen, kidney, and brain, leading to clinical amyloidosis based on patterns.

Purpose of amyloidosis early intervention

Critical because amyloidosis can be reversed if caught early; based on underlying causes or amyloid patterns/distributions.

Periodic Acid-Schiff (PAS) purpose & chemistry

Demonstrates aldehyde groups formed by oxidation of carbohydrates/glycogen; periodic acid oxidizes tissue, Schiff reagent binds aldehydes, causing color change in running water.

PAS chemistry steps & reagents

Periodic acid oxidizes tissue; Schiff reagent (basic fuchsin + HCl + sodium metabisulfite) binds newly-formed aldehyde groups during incubation.

PAS fungal infection counterstain

Light green counterstain; fungal cell walls have high cellulose that binds with Schiff, showing other elements as green.

PAS results for glycogen, fungi, and nuclei

Glycogen, fungi, basement membranes, and mucosubstances stain pink to red; nuclei stain blue with hematoxylin; other elements green if counterstained.

PAS with Diastase purpose

Used specifically to identify glycogen granules by comparing a diastase-treated section with an untreated control section.

PAS with Diastase methodology & interpretation

Two sections prepared (one buffered diastase, one buffer only); PAS+ in untreated and PAS- in treated section confirms glycogen (treated becomes vibrant rose).

Diastase solution preparation & incubation

Contains alpha/beta amylase; dissolved in phosphate buffer (pH ~6.0) and incubated at 37℃ for one hour before use for optimal effectiveness.

Mucicarmine stain purpose & clinical use

Demonstrates acidic mucins secreted by epithelial cells and stains the capsule of the Cryptococcus organism deep pink or red.

Mucicarmine chemistry & staining

Carmine red dye bound to aluminum acting as a mordant; cell nuclei stained with hematoxylin and other elements with metanil yellow.

Alcian blue pH 2.5 results

Stains carboxylated and weakly sulfated acid mucins blue; nuclear fast red stains nuclei/other elements red to pink.

Alcian blue pH 1.0 results

Stains weakly and strongly sulfated acid mucins blue; water-soluble dye with blue color coming from copper.

Alcian Blue/PAS combination purpose

Combined to simultaneously demonstrate neutral and acid mucins; alcian blue applied first so acid mucins are nonreactive to PAS.

Alcian Blue/PAS acid mucins color

Blue for acid mucins; neutral mucins/PAS+ elements are pink to red; mixtures appear blue/red purple with light hematoxylin counterstain.

Alcian Blue/PAS neutral mucins color

Pink to red for neutral mucins and other PAS+ elements; acid mucins remain blue.

Colloidal Iron stain chemistry

Acid mucins bind colloidal ferric ions at low pH; Prussian Blue reaction introduces potassium ferrocyanide, making dark blue ferric ferrocyanide.

Colloidal Iron clinical use & sensitivity

More sensitive when staining for acid mucins in small amounts, such as in mesothelioma; nuclear fast red used as counterstain.

Congo Red selective affinity & chemistry

Selective affinity for amyloid via non-polar hydrogen bonds with high pH and sodium in solution; produces apple-green birefringence under polarized light.

Congo Red polarized light result

Amyloid appears pink/red under nonpolarized light and exhibits diagnostic apple-green birefringence under polarized light.

Congo Red section thickness requirements

Sections must be cut thick at 7 to 10 microns to show birefringence properly; sections too thin show blue/red, too thick show yellowish birefringence.