Examining Cells And Tissues

Question 1

Name the four types of tissue

Answer 1

Connective
Epithelial
Muscle
Nervous

Question 2

Define tissue

Answer 2

Tissue = woven in Latin

Group of specialised cells that have a distinct structure and function

Question 3

Define limit of resolution

Answer 3

Smallest distance by which two objects can be separated and still be distinguished as 2different objects

Question 4

Why is electron microscopy capable of finer resolution than light microscopy

Answer 4

Limit of resolution proportional to wavelength

Electron much smaller wavelength than light therefore much smaller limit of resolution

Question 5

Why is fixation necessary? Name two fixation agents.

Answer 5

Prevent putrefaction
Formalin- light microscopy
Glutaraldehyde- EM

Question 6

Advantages of frozen section

Answer 6

Rapid
Ability to look at surgical specimen quickly
Not need for fixation

Question 7

Disadvantages of frozen section

Answer 7

Decrease stain retention
Decrease cellular architecture can be seen
Opacity

Question 8

What slices a embedded specimen?

Answer 8

Microtome

Question 9

Why are samples embedded?

Answer 9

Sample needs to be translucent and v. Thin to allow light to pass through and prevent diffraction

Question 10

Name two embedding agents

Answer 10

Light- paraffin wax

EM- epoxy Resins/ plastics

Question 11

What the problem with agents tyluol and xylol that dissolve paraffin wax?

Answer 11

Strip lipophilic molecules

Question 12

What is in an H + E stain?

Answer 12

Haematoxylin and Eosin

Question 13

What structures does haematoxylin stain?

Answer 13

Nucleus

Binds acidic structures

Question 14

What structures does eosin stain?

Answer 14

Cytoplasm and ECM

Bind basic structures

Question 15

Name other staining techniques? What are they used to visualise?

Answer 15

Masson’s technique - identify different fibres
Periodic Acid- Schiff-identify anything with a sugar attached

Osmium tetroxide - EM

Question 16

Name 4 biopsy techniques.

Answer 16

Surgery later dissection by histopathologist
Scraping
Sharp needles
Direct venepucture

Question 17

What type of microscopy requires the specimen to be covered in a heavy metals?

Answer 17

transmission electron microscopy

Question 18

Name and describe the two different techniques for immunohistochemistry.

Answer 18

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

Question 19

Name 4 biopsy techniques.

Answer 19

Surgery
Scraping- curettes/scalpel scrapes
Sharp needles-pipelle - endometrium
Venepucture- blood smears

Question 20

What are the advantages of confocal microscopy?

Answer 20

V sharp images

3D

Question 21

What does the phase ring do in phase contrast microscopy?

Answer 21

Straighten the light rays

Question 22

Give some advantages of cell culture?

Answer 22

Control physical environment
Homogeneity of sample
Decrease need for animal models

Question 23

Give some disadvantages of cell culture

Answer 23

Hard to maintain 
High cost 
Dedifferentiation 
Instability/aneuploidy 
3D architecture lost 
Influence of other cells and tissues not maintained

Question 24

What is dark field microscopy?

Answer 24

Use light that is not collected by objective lens

Results in dark background and bright objects