histology intro

Question 1

what is the functions & example of epithelial tissue?

Answer 1

barrier & lining

outer layer of skin

Question 2

what is the functions & example of connective tissue?

Answer 2

structural and functional support

cartilage, bone

Question 3

what is the functions & example of muscle tissue?

Answer 3

specialised for contraction

cardiac cells

Question 4

what is the functions & example of nervous tissue

Answer 4

carries info throughout body via electrical impulses

nerves

Question 5

what is histology?

Answer 5

microscopic study of normal cells and tissues

Question 6

what is pathology?

Answer 6

study of diseased cells and tissues

Question 7

what kind of physical/chemical insults induce alterations in tissue architecture?

Answer 7

infection
extreme heat/cold
cuts/fractures
poison/drugs
genetic & congenital changes
ageing, wear & tear
cancers

Question 8

how can tissue samples ve illuminated?

Answer 8

a beam of light=light microscope

beam of electrons=electron microscope

Question 9

what are the differences between LM & EM?

Answer 9

LM basic cellular structure
EM ultrastructure
LM resolution = 0.2 microm
EM resolution =1 nm
LM most commonly used

Question 10

what are the 6 stages of microscopy?

Answer 10

1. specimen collection
2. fixation
3. dehydration
4. embedding
5. sectioning
6. viewing
7. staining

Question 11

describe specimen collection

Answer 11

biopsy tissue
depends on type & location
incision/punch -skin/oral
needle-organs/lumps-imaging rn to guide
endoscopic- tube with light & camera

Question 12

describe fixation

Answer 12

preserves structural arrangement
terminates all biochemical reactions & prevents tissue decomposition
eg formaldehyde/glutaraldehyde

Question 13

describe dehydration

Answer 13

paraffin embedding not compatible with water, so removed using a series of graded alcohols, gradually to prevent distortion

Question 14

describe embedding

Answer 14

tissue must be supported to allow thin sections to be cut
resins/paraffin wax
paraffin not compatible w/ alcohol so replaced w/ xylene

Question 15

describe sectioning

Answer 15

sections must be thin & flat, ideally single layer cells
transparent-light/ electrons can pass thru
embedded specimens sectioned using microtome
approx. 7microm thick
mounted on glass slides
where tissues are sectioned makes a big difference to tissue architecture

Question 16

describe staining

Answer 16

most cells colourless
staining makes cell/components visible
wide variety methods for LM
allows identification dif cell and tissue features
most LM stains are aqueous not compatible with paraffin
reversal of dehydration steps to remove paraffin wax & replace w/ water

Question 17

what is H&E

Answer 17

most common
haematocylin stains acidic structures blue/purple
eosin stains basic structures red/pink

Question 18

what is periodic acid-Schiff reaction? (PAS)

Answer 18

stains complex carbohydrate magenta

mucins produced by goblet cells, brush borders and basement membranes are PAS positive

Question 19

what is masson trichrome?

Answer 19

stains CT
nuclei & basophilic structures stain blue
collagen green/blue
cytoplasm, muscle, RBC, keratin stain red

Question 20

what is immunohistochemistry?

Answer 20

utilises antibody specificity for antigen
antibodies rn to identify substance of interest
antibody conjugated to indicator

Question 21

what are another 3 stains?

Answer 21

alcian blue
-mucin & cartilage blue
van gieson
-collagen red, nuclei, erythrocytes, cytoplasm yellow
reticulin stain
-reticulin fibres blue/black

Question 22

how are permanent mounts made?

Answer 22

stained sections dehydrated once again to replace water w/ xylene
mounting medium, coverslip seal protect sections