Intro To Histology Flashcards
What are the 4 mains tissue types?
Epithelial
Connective
Muscle
Nervous
Describe the function of nervous tissue and give an example.
Carries information throughout the body via electrical impulses
eg. Nerves
Describe the function of muscle tissue and give an example.
Specialised for contraction
Eg. Cardiac cells
Describe the function of connective tissue and give examples.
Provide structural and functional support
Eg. Cartilage and bone
Describe the function of epithelial tissue and give an example.
Barrier and lining tissue
Eg. Skin
Describe features of a reticulin stain.
Stains reticulin fibres blue black
(Component of connective tissue)
Often combined with h&e
Describe features of van gieson stain.
Stains collagen red
Stains nuclei, erythrocytes and cytoplasm yellow
Describe features of alcian blue.
Stains mucin and cartilage blue
Can be combined with other stains eg H&E
Describe creatures of Immunohistochemistry
Antibodies required to identify substance
Uses antibody specificity for antigen
Antibody conjugated to an indicator
(Enzymatic or fluorescent)
What is an antigen?
Molecule that binds to antibody to reveal components
Describe features of Masson trichrome stain.
Different colours depending on tissue
Purple = epithelial (nuclei and basophillic structure)
Green/blue = collagen, connective tissue
Red = cytoplasm, muscle, keratin, red blood cells
Differentiates different types of cells
Describe features of a periodic acid-shiff reaction. (PAS)
Stains complex carbs magenta
Can be combined with H&E
Mucins produced by goblet cells, brush borders and basement membranes are PAS-positive
Dark stain = packed with carbs
Describe features of Haematoxylin and Eosin stain (H&E)
Most common stain
Flexible
H= basic dye so stains acid blue/purple (nucleic acids)
E= acidic dye so stains basic red/pink
(Cytoplasmic proteins)
Binds to nucleus and cell dense areas = darker stain
Define histology and pathology.
Histology is the study of normal cells & tissues
Pathology is the study of diseased cells & tissues
Describe differences between light microscopy and electron microscopy.
LM = reveals basic cell structure, resolution isn’t as strong, can see wider view, compatible with stains, cheaper
EM =reveals ultra structure, view higher magnification
Why must steps be reversed during staining?
Most stains for LM are aqueous
Therefor not compatible with paraffin
Reverse steps of dehydration replace paraffin wax with water
Describe staining.
Makes cell and components visible
Lots of methods available for LM
Allows for identification of different cells and tissue features
Describe sectioning.
Important so tissues can be visualised under microscope
Sectioned using microtome
Sections placed on glass slides
Should be transparent
Describe embedding.
Supports tissue allowing thin sections to be cut without disturbing structure
Resin/ paraffin wax usually used
-paraffin not compatible with alcohol
Therefor alcohol replaced with xylene
Describe dehydration.
Paraffin is not compatible with water but can react so has to be gradually dehydrated with ethanol.
Prevents distortion
Water removed using series of graded alcohols
Describe fixation.
Preserves structural arrangement of cells and extracellular components
- terminates all biochemical reactions ie. Inhibits enzyme to stop degrading tissue & prevents microbial growth
Eg formaldehyde of glutaraldehyde
Describe specimen collection.
(3)
1) incision/ punch biopsy = skin of oral surfaces, used when it’s accessible
2) needle biopsy = organs or lumps below skin - used when not visible
3) endoscopic biopsy = colon, bladder, lung etc.
flexible tube with light and camera cutting tools used to collect skin specimen
Name the 7 steps required for microscopy?
1) specimen collection
2) fixation
3) dehydration
4) embedding
5) sectioning
6) viewing
7) staining
What are the 4 main bio molecules of cells?
Carbohydrates
Proteins
Lipids
DNA/RNA
