Lecture 2

Question 1

Why is a buffered solution used as a fixative. Formalin?

Answer 1

So the conc outside the tissue sample and inside are the same, so water doesn’t move and cause shrinkage.

Question 2

WHAT IS AN ARTEFACT?

Answer 2

PRESENCE OF SOMETHING THAT’S NOT NATURALLY PRESENT e.g from dust.

Question 3

Define Limit of resolution

Answer 3

The shortest distance required to distinguish to points of an object in a microscope

Question 4

Explain why electron microscopes are capable of finer resolution than light microscopes

Answer 4

Electrons have a shorter wavelength. Wavelength is proportional to resolution. Hence lower limit of resolution.

Question 5

What is immunohistochemistry?

What is immunofluoresence?

Answer 5

Antibodies used complementary to the antigen on the organelle. Secondary antibody with an enzyme/ dye attached to it, complementary to the primary antibody. Then add substrate to the enzyme which produces a coloured product.

Immunofluoresence does not require a secondary antibody but rather a fluorescent tag which produces a signal.

Question 6

Confocal light microscopy- advantages

Answer 6

Laser excites a fluorescent dye. Electrons raised to a higher energy level. When electrons de-excites. Light emitted is of a higher wavelength. Light is detected by a CMOS detector. Only part of the light is detected which gives A SHARPER IMAGE and EXAMINE entire depth of tissue.

Question 7

Dark field- advantages

Answer 7

Illuminate an unstained sample.

• Ideal for unstained objects
• You can use living organisms

Question 8

Phase contrast- advantages

Answer 8

Ingest a contrast fluid.
You are able to see the movement thru imaging.
Advantages
-You can see what’s happening in real time

Question 9

Explain the value of histology in diagnosis

Answer 9

Helps to understand the arrangement of cells and tissues in a normal organ system and compare it to the cells and tissues in a patient with abnormalities which can then help diagnose the illness. This can help with prognosis+ effective treatments.

Question 10

What is shrinkage?

Answer 10

Causes the cells to become smaller than they actually are

Question 11

Describe Curretage, needles and trans vascular and which tissues can be sampled by each

Answer 11

Curretage- remove tissue with a Curretage by scraping/ scooping- Used on the uterus
Needle biopsy- Fine, hollow needle inserted into the mass. Sample collected and needle withdrawn. Can be used to take tissue samples from muscles and bones
Trans vascular-

Question 12

Difference between electron and light microscopes?

Answer 12

Electron microscopes are difficult and expensive to prepare and can only view dead objects. It can only produce monochrome images.
The resolution of electron microscopes are much higher than light and magnification is 1,000 more.