| A | B |
|---|
| Clearance angle of a knife | 3° - 8° |
| Bevel angle of a knife | 27° - 32° |
| A preservative | Thymol |
| Standard thickness of a glass slide | 0.5 - 1.0 mm |
| Should not be used with cellodinized slides: | PAS, Mucopolysaccharide methods |
| Two slide adhesives that give the greatest possible adhesion | Celloidin, Resins |
| The solution used in resins that has a tendency to extract dyes | Acetone |
| Section thickness of Routine Work | 4-6µ |
| Section thickness of Myelin & Amyloid | 10µ |
| Section thickness of Small Biopsies | 2-4µ |
| Temperature of slide drying ovens for routine work | 50-60°C |
| Temperature of slide drying ovens for CNS | 37°C |
| Paraffin that has a low plastic point may cause: | Compression due to paraffin being softer |
| To prevent the formation of large crystals in paraffin | Cool blocks rapidly |
| Examples of "soft tissue": | Brain, spinal cord, large Lymph Nodes |
| Sectioning problems that occur in "soft tissue" types: | Compression, Stress lines parallel to knife |
| Examples of hard, bloody or tough tissue: | Thyroid, uterine fibroids, keratinized epithelium, cirrhosis, spleen, blood clots |
| Causes of hard or tough tissue: | Prolonged: fixation, high conc. of alcohol, clearing, overheated paraffin, drying out of tissue in cutting room, shorter processing for biopsies, nature of the tissue |
| "Step Sections" | Requires several slides, Take levels through entire block |
| Crooked Ribbons | Knife and block not parallel |
| Thick Sections or Skipped Sections | Knife or block is loose |
| Compression, wrinkled or jammed together | Knife dull, room to warm, knife tilt too slight, paraffin on knife edge |
| Sections crumble and tear out | Material incompletely dehydrated, soft and musky |
| Split ribbon or length-wise scratches | Nicks in knife, Knife edge dirty, Hard particles in block |
| Set screws loose/Knife holder loose/Excessive knife tilt | Undulations, washboard venetian blind |
| When static electricity occurs while sectioning: | Breathe on block and knife, boil water in room, ground microtome to water pipe |
| Causes of chatter | Dull knife, Overdehydration |
| Sectioning artifact/problem that affects the morphology of the tissue | Overexpansion of sections on waterbath |
| Unstained areas or white spots on stained sections may occur from: | Slides did not stay in oven long enough (improper drying) |
| Holes in tissue section are caused by: | Sectioning or facing too quickly, Excessive dehydration |
| The function of honing | Primary bevel, Remove nicks |
| The function of stropping | Secondary bevel, Finishes knife edge, Actual sharpening |
| When inserting a clean knife into the holder on the Hacker knife sharpener it is important to: | Always clamp the knife in the holder the same way every time |
| The function of lubricants during knife sharpening: | Coolants, Allow metal particles to flow away from knife, Prevents metal chips from lodging in stone |
| The supporting surfaces for abrasives used during sharpening: | Glass plate, Metal plate, Copper & Bronze, Aluminum, Cast Iron |
| The supporting surface that is prone to rust | Cast Iron |
| Types of abrasive powders used during sharpening: | Diamond dust, carborundum, alumina or aluminum oxide, magnesium oxide, Jeweller's rouge, cerric oxide, chromium oxide |
| Over stropping causes | Knife edge to dull and rounds it |
| Knife handles and backs are used for | Hand or manual sharpening |
| Dehydrants | Ethanol, butanol, acetone, isopropanol, methanol |
| Universal solvents | Tert. Butanol, Dioxane, Tetrahydrofuran |
| Advantage of Dioxane | Miscible with water, alcohol, xylene, paraffin |
| Disadvantage of Dioxane | Cumulatively toxic, expensive |
| Solid dehydrant that turns blue when it absorbs water | Anhydrous copper sulfate |
| 3 aromatic hydrocarbons | Benzene, Toluene, Xylene |
| Limonenes are safer than xylene because they are | Less toxic |
| Advantages of xylene | Clears quickly, penetrates rapidly, makes tissue transparent |
| Disadvantages of xylene | Hardens tissue excessively |
| Clearing agent that must be incinerated to be destroyed | Toluene |
| The best aromatic clearing agent | Toluene |
| Why is choloroform not a clearing agent used in staining? | Evaporation & Ventilation |
| What clearing agent helps to soften tough tissue such as uterus? | Cedarwood Oil |
| Aliphatic hydrocarbons | Limonene |
| Effect of incomplete dehydration on tissue blocks | Tissue will shrink, get hard |
| 3 additives that increase adhesiveness of paraffin | Beeswax, Tallow, Lard |
| When heating paraffin at what temperature should the dispenser be set? | 2-4°C higher than the melting point of paraffin |
| Why should paraffin be filtered? | To remove dust/dirt to prevent damage to knife |
| Main purposes of vacuum impregnation | To remove air bubbles in tissue, to remove clearing agent more rapidly, decrease impregnation time by 1/3, prevent hardening of tissue |
| Advantage of agitation in processing | Helps in fluid exchange |
| Advantages of a "closed" processor over "open" processor | Enclosed in a hood or vent, no noxious fumes |
| In an open tissue processor the fluid level above the cassettes in the container must be | 13 mm |
| What is the maximum acceptable thickness of tissue when grossing? | 3 mm |
| Lillie methods for delicate tissue start processing in | 70% alcohol |
| Lillie methods for fatty tissues start processing in | Acetone |
| A clearing agent recommended for uterus and muscle is | Cedarwood Oil |
| Volume of fluid should exceed that of tissue by | 15-20 Volumes |
| Artery is embedded as a | Cross section or on edge if opened lengthwise |
| Needle core biopsies are | Embeded on long axis, parallel to the long axis of mold |
| Cornmeal button that the prosector has divided in half are embedded | On edge, facing same direction |
| Embed muscle biopsies | Cross section and longitudinal section on same mold |
| Curettings (gyn or skin) are embedded | In the center of mold & pushed down so that they do not float |
| Which embedding medium is used to demonstrate lipid and some enzymes? | Carbowax |
| What embedding resin is used in phase micropscopy, bone disease studies for undecalcified sections, and renal biopsies (at 1-2 microns)? | Acrylic resins - the methacrylates |
| Advantages of methacrylates | Support of tissue is greater than with paraffin, shows high enzyme activities with accurate localization |
| The degree of polymerization of Glycol Methacrylate (GMA) is a function of: | Time, Temperature, Concentration of Catalyst |
| Methyl methacrylate is used for | Bone disease specimens and kidney biopsies |
