L.16 Histology

Question 1

L.O.

Answer 1

• Understand the difference between histology and pathology
• Describe the steps involved in tissue processing for microscopy
• Compare magnification to resolution
• Distinguish different nuclei shapes and explain how this can be used to determine cell shape
• Identify and describe the Haematoxylin and Eosin stain in images

Question 2

Histology

Answer 2

Study of bodys cells and tissues and how they are organised into organs

Question 3

Pathology

Answer 3

Study of adnormal or diseased tissue

Question 4

Steps involved in tissue processing

Answer 4

1. Specimen aquisition (fresh tissue)
2. Fixation (preserve structure)
3. Dehydration (remove water)
4. Embedding (stiffen to cut, wax, freeze, resin)
5. Section (improves resolution)
6. Stain ( produces contrast and specific structure identification)

Question 5

Magnification

Answer 5

Process of enlarging the size of an object through opticl instruments

Question 6

Resolution

Answer 6

• The ability to distinguish between 2 closely spaced objects/ details in image
• Smallest distance between 2 points where they can still be seen as seperate things
• Low resolution = blurry and less distinct features

Question 7

Light Microscopy:
- Resolving power
- Max magnification
- Section thickness

Answer 7

• Resolving power = 0.2um - 200nm
• Max magnification = 2000x
• Section thickness = 5um - 10um

Question 8

Electron Microscopy:
- Resolving power
- Max magnification
- Section thickness

Answer 8

• Resolving power = 3nm
• Max magnification = 500,000x
• Section thickness = 0.025um

Question 9

Nucleus under microscope

Answer 9

• Shape of nucleus often dictates the shape of a cell
• Cell mimics the shape of the nucleus

Question 10

Haematoxylin and Eosin stains

Answer 10

Haematoxylin stains:
- Purple = nucleus
- Pink = cytoplasm

Eosin stains:
- Collagen and cytoplasm = shades of pink

Question 11

4x objective lens magnification

Answer 11

• General microscopy of the tissue
• Numerous structures
• Not much detail
• Cannot identify neclei and indicidual cells

Question 12

10x objective lens magnification

Answer 12

• Detail improves identify nuclei
• Cell boarders still indistinguishable

Question 13

20x objective lens magnification

Answer 13

• Can see shapes of nuclei and cells
• Stain characteristics are obvious
• Fewer structures in FOV

Question 14

40x objective lens magnification

Answer 14

• See inside nuclei
• Base membrane of cells can be seen

Question 15

Transmission electron microscopy

Answer 15

• Up to 500,000x magnification
• See inside cells and resolve things 3nm apart