AMCA MHTC flashcards
AMCA MHTC · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Neutral buffered formalin
- A 10% solution of formalin in phosphate buffer, giving about 4% formaldehyde at near-neutral pH; the standard fixative for routine histology.
- Fixative-to-tissue ratio
- The recommended minimum volume ratio of fixative to tissue, generally at least 10:1, ensuring adequate penetration and preservation.
- Formalin fixation rate
- Formalin penetrates tissue at roughly 1 mm per hour at room temperature, so thin 2-3 mm sections fix more rapidly and evenly.
- Bouin solution hazard
- A picric acid, formalin, and acetic acid fixative; picric acid is explosive when dry, so it must be kept moist and handled carefully.
- EDTA decalcification
- A chelating decalcification method that removes calcium slowly while better preserving tissue morphology and antigenicity than acid decalcifiers.
- Tissue processing sequence
- The standard order of dehydration in graded alcohols, clearing in xylene, and infiltration with molten paraffin to prepare tissue for embedding.
- Xylene clearing
- A clearing agent miscible with both alcohol and paraffin; it is toxic and requires ventilation but is standard in paraffin processing.
- Paraffin infiltration temperature
- Molten paraffin infiltration typically occurs at 56-60 degrees C; excessive heat hardens tissue and can reduce antigen preservation.
- Embedding orientation
- Positioning tissue so the desired cut surface faces the block face, with multiple pieces aligned in one plane for serial sectioning.
- Incomplete processing signs
- Soft, wet, or opaque areas in the block indicate inadequate dehydration or infiltration and may require reprocessing before sectioning.
- Routine section thickness
- Paraffin sections for routine H&E are cut at 3-5 micrometers; thinner 2-3 micrometer sections suit biopsies and immunohistochemistry.
- Clearance angle
- The 5-10 degree angle between knife and block that prevents rubbing; too low causes chatter and too high causes compression.
- Floating bath temperature
- A water bath near 40-45 degrees C flattens paraffin ribbons; excessive heat expands tissue and creates artifacts.
- Chatter artifact
- Vibration marks in sections caused by a loose knife or block, hard tissue, or excessive cutting speed; corrected by tightening and slowing.
- Frozen section thickness
- Frozen sections are typically cut at 4-6 micrometers near -20 degrees C; colder tissue shatters and warmer tissue smears.
- Hematoxylin and eosin
- The routine stain in which hematoxylin colors nuclei blue-purple and eosin colors cytoplasm and collagen pink.
- Progressive versus regressive
- Progressive hematoxylin uses controlled staining time; regressive overstains then removes excess dye with acid alcohol differentiation.
- Bluing step
- An alkaline rinse after hematoxylin differentiation that converts the dye to its blue-purple color, often using ammonia water or lithium carbonate.
- PAS with diastase
- PAS stains glycogen and mucins magenta; diastase digestion removes glycogen, so retained staining indicates mucin.
- Masson trichrome
- A special stain coloring collagen blue or green and muscle red, useful for assessing fibrosis and muscle architecture.
- Ziehl-Neelsen stain
- An acid-fast stain detecting mycobacteria as red bacilli against a blue or green counterstained background.
- Prussian blue stain
- A stain for hemosiderin in which acid releases ferric iron that reacts to form a blue pigment.
- Formalin safety
- Formalin is a carcinogen and irritant; it requires ventilation, gloves, eye protection, and separate formalin waste disposal.
- Universal precautions
- Treating all human tissue and body fluids as potentially infectious, requiring gloves, lab coat, and appropriate barriers.
- Sharps disposal
- Blades, needles, and glass go into rigid sharps containers; blades are never recapped or bent by hand.
- Biological waste segregation
- Infectious waste is separated and autoclaved or incinerated per regulations, while formalin waste is collected separately.
- Daily staining QC
- Checking stain quality using control slides and recording reagent lot numbers and expiration dates to verify consistent results.
- Pale nuclei cause
- Pale or weak nuclear staining suggests exhausted hematoxylin, inadequate bluing, or excessive acid-alcohol differentiation.
- Floaters in sections
- Extraneous tissue fragments on slides arise from contaminated water baths, dirty knives, or carryover; clean instruments and change bath water.
- Formalin pigment removal
- Brown-black formalin pigment from acidic unbuffered fixative is removed with saturated alcoholic picric acid.
- Microtome maintenance
- Daily cleaning of blade and stage plus scheduled lubrication and alignment checks prevent chatter and uneven sectioning.
- Reagent labeling
- Each reagent is labeled with preparation date, lot number, and expiration; it is discarded when QC fails or expiration passes.