Introduction

Question 1

What is tissue biology/histology?

Answer 1

Study of the morphological features of normal tissues and the relationship to tissue function

Question 2

What is morphology?

Answer 2

The form and structure of organisms

Question 3

Why must we fix tissue?

Answer 3

Because unfixed tissue will degrade by autolysis

Question 4

What is autolysis?

Answer 4

Self digestion - the destruction of a cell through the action of its own enzymes

Question 5

Give two examples of fixatives?

Answer 5

Alcohol based of formalin

Question 6

How does an alcohol based fixative work?

Answer 6

By denaturing the proteins

Question 7

How does formalin work and what is the active agent?

Answer 7

The active agent is formaldehyde (37%) - it works by cross-linking proteins

Question 8

Why are tissue blocks passed through graded alcohols in the tissue fixation process?

Answer 8

To dehydrate the tissue

Question 9

What are the tissues embedded into?

Answer 9

Paraffin wax

Question 10

What type of block is the tissue embedded into?

Answer 10

A paraffin blox

Question 11

What machine cuts sections from the paraffin block?

Answer 11

A microtome

Question 12

What size are the tissues cut into from the paraffin block?

Answer 12

0.004mm

Question 13

After the sectioning procedure what is done?

Answer 13

The tissue sections are mounted onto a glass slide

Question 14

When the tissue sections are on the glass sides what is done next?

Answer 14

The glass slide sections are stained

Question 15

What does the processing and embedding stage of the preparation process provide you with?

Answer 15

It leaves you with tissues embedded into molten wax

Question 16

If you could describe the preparation of a tissue on a glass side in five stages what would they be?

Answer 16

Processing and embedding
Embedding tissue into paraffin block
Sectioning
Mounted onto a glass slide
Section stained

Question 17

Give an example of a basic dye

Answer 17

Haematoxylin

Question 18

Give an example of an acidic dye

Answer 18

Eosin

Question 19

What are the two main dyes used in tissue fixation?

Answer 19

Haematoxylin and eosin

Question 20

What charge do basic dyes have?

Answer 20

positive

Question 21

What charge do acidic dyes have

Answer 21

negative

Question 22

What charge do basic dyes bind to and why?

Answer 22

Basic dyes are positively charged so they bind to negatively charged tissue components

Question 23

What charge do acidic dyes bind to and why?

Answer 23

Acidic dyes are negatively charged so they bind to positively charged tissue components

Question 24

What is basophilia?

Answer 24

Binding of a basic due to a tissue component

Question 25

What colour does haematoxylin stain?

Answer 25

Blue

Question 26

What components would the basic dye haematoxylin bind to?

Answer 26

Nuclear chromatin, cytoplasmic rna and certain extracellular matrix proteins such as cartilage

Question 27

What is acidophilia?

Answer 27

The binding of an acidic dye with tissue

Question 28

What colour does eosin stain?

Answer 28

pink

Question 29

What components would the acidic dye eosin bind to?

Answer 29

Cytoplasmic proteins including cytoskeleton, intracellular membranes, most extracellular protein fibers, e.g. collagen

Question 30

How many times does a light microscope magnify?

Answer 30

1000x

Question 31

How many times does an electron microscope magnify?

Answer 31

100,000x

Question 32

How does fluorescence microscopy work?

Answer 32

Antibodies or probes with a fluorescent tag introduced