Histology Stains and Microscopic Techniques

Comprehensive vocabulary flashcards covering routine, special histochemical, connective tissue, lipid, hematology, and microorganism stains, along with their characteristic staining colors, cellular targets, and diagnostic features.

Hematoxylin and eosin (H&E)

The most widely used routine histological stain for general tissue architecture and cell morphology; stains cell nuclei blue-purple, cytoplasm and collagen pink, and erythrocytes salmon-pink.

Periodic acid–Schiff (PAS)

A special histochemical stain that colors carbohydrate-rich structures magenta; commonly used to demonstrate glycogen, glycoproteins, neutral mucins, and basement membranes (such as in the kidney, liver, or goblet cells).

Alcian blue

A special histochemical stain that stains acidic mucins and some glycosaminoglycans blue (depending on pH); frequently used to highlight acidic mucus in intestinal goblet cells.

Masson's trichrome

A special connective tissue stain used to distinguish collagen-rich tissue from muscle; collagen typically stains blue or green, while muscle stains red and cytoplasm red/orange.

Osmium tetroxide

A lipid stain and fixative that reacts with unsaturated lipids to produce a black appearance; used to demonstrate lipid-rich structures, myelin, and lipid droplets.

Silver impregnation (reticulin stain)

A special staining technique that demonstrates reticular fiber networks (often type III collagen) by staining them black; commonly applied to liver, lymph node, and bone marrow sections.

Orcein

A special stain that demonstrates elastic fibers, coloring them brown to dark purple depending on the protocol; commonly used to identify elastic lamellae in the aorta.

Toluidine blue

A basic dye used to demonstrate mast cells via metachromasia; stains sulfated glycosaminoglycan-rich granules (such as heparin) purple-red against a blue background.

Metachromasia

A staining phenomenon in which a dye changes its color upon binding to certain highly charged polyanionic structures, such as toluidine blue shifting from blue to purple-red on mast-cell granules.

Perls' Prussian blue

A special histochemical stain that detects ferric iron, including iron in hemosiderin, by producing distinct blue iron deposits; useful for assessing iron accumulation in the liver or bone marrow.

Congo red

A special stain used to detect amyloid deposits; appears red-orange under normal light and displays pathognomonic apple-green birefringence under polarized light.

Apple-green birefringence

The key diagnostic optical property observed when Congo-red–stained amyloid deposits are examined under polarized light.

Ziehl–Neelsen stain

A microorganism stain used to identify acid-fast organisms such as Mycobacterium tuberculosis; acid-fast bacilli appear red against a blue background.

Gram stain

A differential microbiology stain based on cell-wall properties that distinguishes Gram-positive bacteria (purple) from Gram-negative bacteria (pink/red).

Giemsa stain

A blood and hematology stain used for peripheral blood smears and parasite detection (such as malaria); stains nuclei purple-blue and red blood cells generally pink.

Sudan Black B

A lipid stain that colors lipid-rich structures, including myelin and fat droplets, dark blue-black to black.

Oil Red O

A lipid-soluble dye that stains neutral lipids and fat droplets red; primarily used on frozen sections because standard solvent processing extracts lipids.

Verhoeff's stain

A special stain that selectively colors elastic fibers and elastic tissue black; commonly used to demonstrate elastic lamellae in arteries.

Van Gieson stain

A connective tissue stain used to differentiate collagen from muscle; typically stains collagen red and muscle/cytoplasm yellow.

Mallory trichrome

A trichrome stain used to highlight connective tissue architecture and fibrosis; characteristically stains collagen blue and muscle red.

Luxol fast blue

A specialized nervous tissue stain used to demonstrate myelin sheaths in neural tissue sections by staining myelin blue.

PTAH (phosphotungstic acid–hematoxylin)

A special stain used in histology to demonstrate selected muscle striations and fibrin, rendering these target structures blue-purple.

Methylene blue

A basic dye that colors selected acidic tissue components and microorganisms blue in various laboratory preparations.

Leishman stain

A Romanowsky-type blood and hematology stain used on peripheral blood films to demonstrate blood-cell morphology and blood parasites, producing purple-blue and pink tones.

Nuclear fast red

A histological counterstain used to stain cell nuclei red to pink-red in selected staining protocols.

Aldehyde fuchsin

A special stain that highlights elastic fibers and certain cellular granules purple to violet depending on the protocol.

Safranin O

A special histological stain that colors cartilage proteoglycans red-orange; widely used in cartilage and joint tissue studies.

Routine stain

A general histological preparation (e.g., H&E) used to demonstrate broad tissue architecture, general cell morphology, and overall organ identification.

Special stain

Any selective histological or histochemical staining method used to visualize specific chemical components, extracellular matrix elements, or microorganisms.

Frozen section (lipid staining principle)

A physical tissue preparation method essential for demonstrating neutral lipids, utilized because standard paraffin embedding and processing solvents dissolve and extract lipid content.