Lecture 2- How To Examine Cells And Tissues Flashcards
Define a tissue
- a tissue terms to ‘woven’ in Latin. It is a group of specialised cells that work together to produce a particular function.
Define limit of resolution
Minimum distance at which two objects can be distinguished.
What are the 4 types of tissue
1( nerve tissue
2) epithelial tissue
3) connective tissue
4) muscular tissue
What are 4 differences between TEM and light microscope?
1) TEM has a resolution of 0.25 nm whereas light microscope has a resolution of 0.25 micrometres.
2) light microscope has a magnification of 600 x whereas TEM has a magnification of 500,000 x
3) TEM is expensive to prepare a microscopic slide whereas light is cheaper
4) TEM produces monochrome Images whereas light produces coloured images.
What are the 4 requirements needed to prepare a microscopic slide under light microscopy?
1) specimen needs to be translucent - cut thinly
2) needs to be fixated and preserved to prevent putrefaction.
3) needs to actually fit the equipment
4) stain !
How do you preserve the specimen?
- using fixative formalin which is 37% formaldehyde which is supplemented with 0.9% Nacl.
- this is isotonic to ICF, which allows the formaldehyde to penetrate through the specimen which allows to react with amino groups of amino acids which forms methylated bridge with proteins.
What is a requirement of the fixation chemical?
- must be buffered.
What allows the specimen to be sliced thinly ?
- paraffin was.
- firstly, specimen must be dehydrated in different conc of alcohols
- then immerse in hot paraffin wax and leave overnight
- will form a mould , then add more paraffin wax and cool at room temp.
Why does H&M’s E stains do not identify lipids?
- first specimen is dissolved in xylene/toluene which strips all lipophillic molecules.
What is an exemption of fixation through fixative formalin?
- using diagnostic frozen section
What are the dial/advan of paraffin wax and frozen section
- paraffin was has better clarity than frozen section
2) paraffin wax takes longer (24-28 hrs) than frozen section 10-20 min)
3) pAraffin wax is permanent whereas frozen section lasts months only.
What is another method of staining?
- immunohistochemistry and immunofluroscence
- both use labelled antibodies that target antigens nd bind complimentary to them.
- immunofluroscence uses labelled dyes.
What images do confocal microscopes produce?
Take multiple 2D images at 1-10 diameters.
COMPUTER lines them up and creates Z stack= 3D
What are 3 examples of cell culture?
1) homogeneity of sample
2) have control over environment
3) less need for animal models
What are disadvantages of cell culture?
- difficult to maintain
2) costly
3) 3D structure is lost
