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Lipids and Pigments - Coggle Diagram

- - - - Colour dependent on pigment density
        
        Extra histochemical stains used
  - - - Chemical deposits after death
    - - Tissue products with physiological function
        
        e.g. metabolic processes
    - - Foreign products enter during life
        
        Via inhalation or implantation to skin
        
        e.g. minerals
  - - - Brown/black after acid fixation
      - Found particularly in haemorrhagic tissues
      - Removed with picric acid
    - - Brown/black
      - Similar to formalin
      - Formed in/near RBCs with parasitic infection
    - - Black
      - Remove with iodine + sodium thiosulphate
    - - Yellow/brown after potassium dichromate fixation + insufficient washing pre-dehydration
      - Remove with acid alcohol
  - - - Red/brown bilirubin
      - Green biliverdin
      - Haemolysis product
      - Accumulates in liver/haemolytic diseases + injury to bile ducts/flow
      - Jaundice indicates high bile pigment levels
      - H&E stain - bright purple/orange/pink stain
      - Primary + secondary cirrhosis
    - - Formed in older tissues
        
        Wear + tear pigment
      - Formed by lipid oxidation
      - Cell lacks mechanisms for transport - accumulates
      - Yellowed sclera in older people - lay-down of lipofuscin
      - Brown
      - Found around nucleus of mainly heart, brain + muscle cells
      - Stained by sudan black, PAS, Schorl's + Long Ziel-Nehlson technique confirmatory
    - - Black/brown
      - Found in hair, eyes, skin, brain + melanoma
      - Excessive can be pathological e.g. melanomas when melanocytes deregulate + produce excessive pigment
      - Pathological when penetrates deeper than basal layer + into macrophages/lymphocytes
      - Macrophages scavenge the melanocytes inc. melanin
    - - Fe3+ state storage of haemosiderin
      - Fine brown
      - Deposited when body has high iron levels
      - Found particularly in liver, bone marrow + spleen
      - Excessive recycling of RBCs in disease e.g. sickle cell
      - Perl's Prussian blue is confirmatory
    - - Gut uptake by vit. D
      - Found in teeth/bones
      - Osteoporosis - low bone density, low Ca2+
      - Pathological accumulation in CKD
      - Identified by Von Kossa staining (silver impregnation) or Alizarin (red dye)
    - - Product of oxidase enzyme metabolism
      - Should not be detectable in histochemistry
      - Accumulates in Wilson's disease
      - Ring around iris of eye - copper accumulation
        
        Genetic or intake
      - Shikita is discriminatory stain
    - - Purine nucleotide breakdown product
      - High uric acid in kidney disease, obesity, diabetes
      - Gout - crystallisation in joints
        
        Birefringent properties seen under polarising microscope
- - - - Condenser
        
        Polariser 1
        
        Specimen
        
        Objective lens
        
        Polariser 2
        
        Light structures observed against dark background
        
        Crossed orientation to polariser 1. Only light from birefringent structures can pass
        
        Magnification
        
        Birefringent structures split light into different orientation
        
        Single orientation of light
        
        Focusses
      - Unpolarised light