Microscopic Structure and Function

Question 1

What are the 4 tissues in the body?

Answer 1

Nerve tissue
Epithelial Tissue
Connective Tissue
Muscle tissue

Question 2

What are some features of Epithelial tissue?

Answer 2

Often on the edge of a tissue
Always have a basement membrane on the basal
Often secrete something from its apical surface
Held together by strong anchoring proteins
Communicate through junctions at their lateral and basal surfaces

Question 3

What are the main cells in connective tissue?

Answer 3

Fibroblasts
Chondrocytes
Osteocytes/blasts/clasts
Stem cells, progenitor cells, bone marrow, blood, adipocytes

Question 4

What are the main products in connective tissue?

Answer 4

Fibres
Ground substance
Wax and gel-like material

Question 5

What are the main types of muscle cells?

Answer 5

Striated such as cardiac and skeletal muscle

Non-striated such as smooth muscle

Question 6

What is the limit of resolution?

Answer 6

The smallest distance by which two objects can be separated and still be distinguishable as two separate objects. This means that a light microscope won’t be able to see as tiny objects as an electron microscope.

Question 7

What are some pros and cons of light microscopy?

Answer 7

Natural colours
Large field of view (sometimes good sometimes not)
Cheap and easy prep
Can view living objects
Low magnification

Question 8

What are some pros and cons of electron microscopy?

Answer 8

Only monochrome
Limited field of view (sometimes good sometimes bad)
Difficult and expensive prep
Can only view dead things
High magnification

Question 9

How is a transmission electron microscope (TEM) prepared?

Answer 9

Fixed with glutaraldehyde
Embedded in epoxy resin
Stained with osmium tetroxide
Use a microtome with diamond knives

Question 10

How is a scanning electron microscope (SEM) prepared?

Answer 10

Fixed with glutaraldehyde
Embedded in epoxy resin
Stained with osmium tetroxide

Question 11

Why is fixation and preservation of the tissue used?

Answer 11

To prevent putrefaction

Question 12

What are some requirements of light microscopy?

Answer 12

Need to preserve the tissue from rotting. Usually done by formalin.
Need to embed the tissue in something that allows it to be sliced very thinly. Usually done by melted paraffin wax that sets hard when it cools down.
Need to stain the tissue in order to see cell components. Usually eosin and haematoxylin.

Question 13

What does haematoxylin stain?

Answer 13

The nucleus and DNA. It stains nucleic acids.

Question 14

What does eosin stain?

Answer 14

Cytoplasm and ECM. For example proteins and collagen

Question 15

What are some pros and cons regarding paraffin wax formalin fixed preparation vs. frozen section?

Answer 15

PWFF = 
Fixed tissue
Takes a long time to make 24-48 hrs
Can save the tissue as long as you want
Clarity
Pathological diagnosis

FS=
Fresh tissue
Quickly made 10-20 minutes
Denatures quickly (months)
Opacity
Intraoperative consultation

Question 16

What needs to be maintained constant in the internal environment regarding histology?

Answer 16

Conc. of O2, CO2, salt and other electrolytes
Conc. of nutrients and waste products
pH
Temp
Volume and pressure of fluid and cell compartments

Question 17

What are some advantages of cell culture?

Answer 17

Absolute control over physical environment
Homogeneity of sample
Less need for animal models

Question 18

What are some disadvantages of cell culture?

Answer 18

Hard to maintain
Only grow small amount of tissue at a high cost
Dedifferentiation
Instability and aneuploidy
3 dimensional architecture is lost
Influence of other cells and tissues is not maintained

Question 19

How do you procure a tissue for examination?

Answer 19

Pipelle, scratching, full ‘ectomy’ as in a hysterectomy.

Biopsy.