Examining Cells And Tissues Flashcards
Name the four types of tissue
Connective
Epithelial
Muscle
Nervous
Define tissue
Tissue = woven in Latin
Group of specialised cells that have a distinct structure and function
Define limit of resolution
Smallest distance by which two objects can be separated and still be distinguished as 2different objects
Why is electron microscopy capable of finer resolution than light microscopy
Limit of resolution proportional to wavelength
Electron much smaller wavelength than light therefore much smaller limit of resolution
Why is fixation necessary? Name two fixation agents.
Prevent putrefaction
Formalin- light microscopy
Glutaraldehyde- EM
Advantages of frozen section
Rapid
Ability to look at surgical specimen quickly
Not need for fixation
Disadvantages of frozen section
Decrease stain retention
Decrease cellular architecture can be seen
Opacity
What slices a embedded specimen?
Microtome
Why are samples embedded?
Sample needs to be translucent and v. Thin to allow light to pass through and prevent diffraction
Name two embedding agents
Light- paraffin wax
EM- epoxy Resins/ plastics
What the problem with agents tyluol and xylol that dissolve paraffin wax?
Strip lipophilic molecules
What is in an H + E stain?
Haematoxylin and Eosin
What structures does haematoxylin stain?
Nucleus
Binds acidic structures
What structures does eosin stain?
Cytoplasm and ECM
Bind basic structures
Name other staining techniques? What are they used to visualise?
Masson’s technique - identify different fibres
Periodic Acid- Schiff-identify anything with a sugar attached
Osmium tetroxide - EM
Name 4 biopsy techniques.
Surgery later dissection by histopathologist
Scraping
Sharp needles
Direct venepucture
What type of microscopy requires the specimen to be covered in a heavy metals?
transmission electron microscopy
Name and describe the two different techniques for immunohistochemistry.
Immunofluorescence- primary ab labelled with fluorescent dye
Indirect method- 2 ab’s second ones tagged to allow addition of chemical that causes precipitate to be formed that can be visualised
Name 4 biopsy techniques.
Surgery
Scraping- curettes/scalpel scrapes
Sharp needles-pipelle - endometrium
Venepucture- blood smears
What are the advantages of confocal microscopy?
V sharp images
3D
What does the phase ring do in phase contrast microscopy?
Straighten the light rays
Give some advantages of cell culture?
Control physical environment
Homogeneity of sample
Decrease need for animal models
Give some disadvantages of cell culture
Hard to maintain High cost Dedifferentiation Instability/aneuploidy 3D architecture lost Influence of other cells and tissues not maintained
What is dark field microscopy?
Use light that is not collected by objective lens
Results in dark background and bright objects
