Histological Methods Flashcards
Classify skin and its tissue type
organ; epithelial + conn.
Classify fascia and its tissue type
tissue; connective
Classify tendons and its tissue type
dense, regular conn. tissue; connective
Classify aponeurosis and its tissue type
tissue; connective
Classify bone and its tissue type
organ/tissue; variety of connective
Classify blood vessels and its tissue type
organ/tissue; epithelial/connective/muscular
Classify nerves and its tissue type
tissue/organ/system; nervous
Classify muscle and its tissue type
organ/tissue; muscular
What is a plain of section
- the part of the specimen you’re looking at
- how 3D structures may appear when thin sectioned in different ways
- essentially different point of views of the same structure
What is the resolution power of an electron microscope
200nm
1cm= (mm)
10
1mm=(micrometres)
1000
1micrometre=(nm)
1000
1nm=(A)
10
Which methods of fixation are used in light microscopy
perfusion, immersion
Which methods of fixation are used in e microscopy
perfusion
What is perfusion
pumping fixatives into blood supply of animal to freeze tissues
*faster than immersion
What is immersion
anesthetizing the animal, taking a specific organ, plopping it into fix which penetrates it and freezes the tissue
Which fixatives are used in light microscopy
- formalin
- mercuric chloride
- picric acid
- Bouin’s Fluid
Which fixative is used in e microscopy
glutaraldehyde
Why is perfusion preferable in e microscopy
since we’re looking at finer details we need to fixate the specimen faster
List the 11 steps of preparing a slide in terms of light microscopy
- fixation
- dehydration (using increasing concentrations of ethanol to get rid of water)
- clearing (xylene-paraffin solvent to get rid of ethanol)
- infiltration (mixing xylene with paraffin wax to make substance more liquidy)
- embedding (100% paraffin, wax block)
- sectioning (microtome, slice = 5 microns)
- mounting(glass slide)
- removal of paraffin(using xylene)
- rehydration(using ethanol, decreasing concentrations, get back to H2O)
- staining (hematoxylin/eosin)
- light microscopy
Why do we use increasing concentrations of ethanol to remove water instead of using 100% right away
osmotic pressure would be too high, causing tissue to burst
List the steps of preparing a slide in terms of electron microscopy
- fixation
- dehydration (same as light)
- clearing(propelyne glycol-epoxy solvent to get rid of ethanol)
- infilitration(propelyne glycol and plastic)
- embedding(100% plastic block)
- sectioning(ultramicrotome, slice =5nm)
- mounting(metal grid)
- staining(lead citrate &/or histochemical rxns)
- transmission electron microscopy
Why does e microscopy use plastic
it’s harder so we can make thinner slices, e are shot at it and it won’t show up in the images
What is hematoxylin
stain used in light microscopy, basic, blue/purple, stains nucleus and acidic structures
What is eosin
stain used in light microscopy, acidic, pink, stains cytoplasm+collagen
What are characteristics of lead citrate
stain used in e microscopy, no specific colour, sticks to proteins, stains membranes with various affinity, doesn’t stain cytoplasm
What are basophilic structures
those containing nucleic acids like ribosomes and the nucleus and regions in cytoplasm that are rich in RNA
What are acidophilic (eosinophilic) structures
intra/extracellular protein, most of cytoplasm
Do structures have to be acidic or basic to be named basophilic or acidophilic
no, naming is based on affinity to dyes
What is an electron lucent structure
a “light space” that is created when electrons pass through the grid/slide/specimen and don’t hit anything
What is an electron dense structure
a dark space created from electrons hitting off the lead citrate and bouncing away
What is the magnification of a light microscope
1000x
What is the magnification of an electron microscope
160 000x
