Light Microscopy Flashcards
State the relationship between milli-, micro- and nanometers.
Meter Millimetre =10^-3 m Micrometer = 10^-6 m Nanometer = 10^-9 m Angstrom = 10^-10 m
Define tissue
A collection of cells specialised to perform a particular function
Define organ
Aggregations of tissues constitute an organ
Define histology
The study of the structures of tissues by means of special staining techniques combines with light and electron microscopy
How is histology valuable in diagnosis?
Doctors will not give treatment until a diagnosis has been confirmed by a histopathologist
A biopsy and histology is final proof of a disease
Histology can differentiate between different diseases with similar symptoms
Define biopsy
The removal of a small piece of tissue from an organ or the body for microscopic examination
What is a smear and what tissues does it sample?
Collect cells be spontaneous or mechanical exfoliation
Cervix
Buccal cavity
What is curettage and what does it sample?
Removal of tissue by scooping or scraping
Endometrial lining of uterus
What is needle biopsy and what does it sample?
Putting a needle into tissue to gather cells Brain Breast Liver Kidney Muscle
What is direct incision and what does it sample?
Cutting directly into tissue of interest for removal
Skin
Mouth
Larynx
What is endoscopic biopsy and what does it sample?
Removal of tissues via instruments through an endoscope
Lung
Intestine
Bladder
What is transvascular biopsy and what does it sample?
Removal of tissue via a vein
Heart
Liver
Why do tissues need to be fixed?
Macro molecules are cross linked, preserving cellular structure
Prevents autolysis
Prevents putrefaction
Name 3 fixatives
Formaldehyde
Glutaraldehyde
Ethanol
How does tissue fixing lead to shrinkage artefacts?
Dehydration the rehydration during slide preparation can lead to abnormalities in the slide i.e. shrinkage artefacts
What does haematoxylin stain?
What colour?
Why?
Acidic cell components
Nucleolus, chromatin
Purple/blue
Basic dye attracted to acidic cell components
What does eosin stain?
What colour?
Why?
Basic cell components
Cytoplasmic proteins, extracellular fibres
Pink
Acidic dye attracted to basic components
What doe PAS stain and what colour?
Periodic Acid- Schiff stains carbohydrates and glycoproteins magenta
What is phase contrast microscopy?
What are its advantages?
Use of the interference effect of two combining light waves
Enhancing the image of unstained cells
Produces an image at heightened contrast
What is dark field microscopy?
What are its advantages?
The exclusion of unscattered beams from the image
Live and unstained samples
Image from scattered rather than transmitted light
What is fluorescence microscopy?
What are its advantages?
Target molecule stained with fluorescent antibody or labelled genetically with a fluorescence protein
Multiple fluorescence stains can be used in one sample
Can be used to see individual substances/structures within the cell
What is confocal microscopy?
What are its advantages?
Tissue labelled with one or more fluorescent probes
Eliminates out of focus light flare
3D images can be produced from several 2D images
Imaging of living specimens
