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Exam revision (Melanoma (Cell types invaded, Features and Functions of the…

- - - - Lids must be tight and container placed into sealable plastic bags
      - Collected specimens should be sent to the cytology laboratory without delay.
      - Specimens must be labelled and biohazard stickers used for high-risk specimens
    - - Cervical Smears (Pap smear)
      - Respiratory Tract (Sputum)
        
        Usually collected on 3 consecutive days
        
        Early morning is preferred collection time
        
        Needs to come from deep cough (not spit/saliva)
        
        Collected into a sterile container
  - - - Squamous
        
        lung alveoli
        
        glomerular capsule of kidneys
        
        lines blood vessels
        
        serous membranes
      - Cuboidal
        
        lines surface of ovary
        
        follicles of the thyroid gland
        
        ducts of the pancreas
        
        kidney tubules
      - columnar
        
        lines the internal surface of the gastrointestinal tract (GIT)
        
        part of the respiratory/ reproductive tract
    - - Squamous
        
        Lines mouth
        
        Oesophagus
        
        vagina
        
        Non-keratinised
        
        anus
      - columnar
        
        lines ducts of some large glands
        
        forms the conjunctiva lining the eyelids
    - - Columnar
        
        lines trachea
        
        Epididymis
        
        male urethra and many glands including the intestine
    - - only lines the excretory urinary passages
  - - - Consequences of air-dried samples:
        
        Increase in eosinophilic staining
        
        Apparent nuclear enlargement
        
        Poor staining
    - - 95% ethyl alcohol is used for most routine preparations.
- - - - Frozens
        
        Microscope used
        
        Light microscope
        
        Advantages and disadvantages
        
        Clinical samples
        
        Advantages
        
        "Rapid diagnosis usually via frozen sections
        
        Resin processing is less common
        
        fixation
        
        Disadvantages
        
        Morphology not as good compared to wax
        
        Obtaining serials difficult
        
        Advantages
        
        Does not dissolve lipids
        
        Preserves fixative sensitive proteins
        
        (enzymes and antigens)
        
        The sample is frozen with liquid nitrogen and isopentane or on dryice in an embedding medium (OCT)
        
        Preparation of fixed samples for cryoprotection
        
        Fix samples immediately (Overnight)
        
        Rinse with phosphate buffered saline (PBS)
        
        30% sucrose: OCT
        
        Samples sink to bottom when cryoprotected
        
        30% sucrose: PBS
        
        Pure OCT to remove sucrose
        
        Ready to freeze
        
        Storage of Frozen samples
        
        In minus 80 degrees Celsius Freezer
        
        Seal sample with OCT
        
        Avoid dehydration artefacts
        
        Special processing bone
        
        Needs to be decalcified
        
        Rapid decal solution used for diagnostics
      - Resin/plastic
        
        Microscope used
        
        Light Microscope
      - Paraffin Wax Processing
        
        Microscope used
        
        Light Microscope
        
        Dehydration
        
        Reduces shrinkages and hardening of artefacts
        
        Start with low grades of alcohol
        
        Basics
        
        Fits into processing cassette
        
        Correct labelling
        
        Use Pencil
        
        Barcodes
        
        Clearing agents (toxins)
        
        Examples
        
        Toluene
        
        Chloroform
        
        Xylene
        
        Reasoning
        
        Advantage
        
        Make tissue appear translucent
        
        High refractive index
        
        Disadvantage
        
        Harden Tissue
        
        Results in brittle blocks
        
        Warnings
        
        Hot Wax
        
        Melting point usually 56 degrees Celsius
        
        Harder waxes higher the melting point
        
        Processes
        
        Wax Pellets
        
        Auto processors have 2 or 3 wax tanks
        
        Molten wax kept in 60 degrees Celsius tanks
        
        Wax Infiltration
        
        Final stage of processing
        
        All water removed from tissue
        
        All alcohol removed from tissue
        
        Vacuum Systems
        
        Help solvents penetrate tissues
        
        Removes trapped air
        
        Failure to remove air bubbles can cause problems during sectioning
        
        Embedding the tissues
        
        The final step to wax processing is to embed the tissue into wax and allow it to set into a hard block rendering it suitable to section
        
        The holding tank of molten wax where the cassettes are placed immediately after processing and removal from machine
        
        The central part where wax is dispensed from another molten wax tank
        
        The cold plate used to set the wax by rapid cooling
  - - - What is being analysed or visualised