Introduction to Histology

Question 1

What is Histology and why we study histology

Answer 1

Histology is the study of tissue and we study histology because its helps to understand the functioning of the body and structures related to functioning of the body

Question 2

Name two types of Microscopy and simple differentiates them.

Answer 2

Light and Electron microscopy.
Light Microscopy- Color image and lower magnification
Electron Microscopy- black and white image, high resolution and magnification and ultrastructure

Question 3

Name two types of electron microscopy and differentiates them.

Answer 3

Scanning Electron Microscopy - 3D images, restricted from surface structures and conceal internal structure
Transmission Electron Microscopy - 2D images, requires more ultrathin section, Beam must pass the spacemen and more informative and ultrastructure.

Question 4

Polychromatic Microscopy and Observe large area of specimen

Answer 4

Light microscopy

Question 5

Monochromatic, Small visualization area, and fewer staining methods.

Answer 5

Electron microscopy

Question 6

If the tissue is not fixed what its can creates?

Answer 6

Artefacts

Question 7

Disadvantages of electron microscopy

Answer 7

Time consuming and costly

Question 8

What is enzyme histochemistry?

Answer 8

The activity of the enzyme can be seen by staining a specific substrate or end product.

Question 9

What is Immunochemistry?

Answer 9

antibodies raised against specific cellular components (antigen) and then paired with visual markers specific to light and electron microscopy.

Question 10

Formaldehyde and glutaraldehyde are examples of what?

Answer 10

Fixative

Question 11

What is fixation

Answer 11

causes cross-linking of macromolecules. reducing cell activity as well as allow cells to be stained better

Question 12

Process before staining

Answer 12

Tissue is sectioned (cut into thin slices)
Specimens are dehydrated with organic solvents (ethanol).
Then embedded into a hard medium (paraffin wax).
Process is as follows: fixation, dehydration, embedding, sectioning and finally staining.

Question 13

Basic dye.
Stains acidic structures purplish-blue.
Best stains: Nuclei, ribosomes, rough endoplasmic reticulum

Answer 13

HAEMATOXYLIN

Question 14

Acidic dye.
Stains basic structures red or pink.
Best stains: cytoplasm, red blood cells, muscle fibres, collagen.

Answer 14

Eosin

Question 15

Histochemical stain.
Stains complex carbohydrates a deep red colour (magenta).
Those that stain with this are termed PAS-positive.
Best stains: mucin, glycogen in hepatocytes, basement membranes

Answer 15

Periodic acid-schiff reaction (PAS)

Question 16

Connective tissue technique.
Demonstrates supporting tissue elements.
Three colours produces:
Nuclei, basophilic structures – blue.
Collagen – green.
Cytoplasm, muscle, erythrocytes – red.

Answer 16

Masson Trichome

Question 17

Mucin stain, used with H&E or with van Gieson stains.
Certain types of mucin are stained blue.
Cartilage also stained blue.
When combined with van Gieson, the alcian blue colour appears green.

Answer 17

Alician blue

Question 18

Connective tissue method.
Stains:
Collagen – red.
Nuclei – blue.
Erythrocytes and plasma – yellow.
When used with elastin stain, elastin appears blue/black.
Particularly useful stain for skin and blood vessels.

Answer 18

Van Gieson

Question 19

Demonstrates reticulin fibres of supporting tissue.

Stained blue/black.

Answer 19

Reticulin

Question 20

Connective tissue technique.
However, also used for fine cytological detail – in epithelium.
Nuclei – bright red.
Collagen, mucin and basement membrane – blue.
Muscle and red blood cells – orange.

Answer 20

Azan

Question 21

Used for staining blood cells.
Nuclei stained dark blue-violet.
Cytoplasm stained pale blue.
Erythrocytes stained pale pink

Answer 21

Giemsa

Question 22

Will differentially stain tissue in thin epoxy resin.
Used in high resolution investigation of glomerulus (structure in kidney) and high resolution light microscopy of nerves..
Stains mast cell granule reddish-purple in paraffin sections

Answer 22

Toluidine Blue

Question 23

Applied to acrylic resin sections of undecalcified bone.
Distinguishes between mineralised bone and unmineralized osteoid.
Haematoxylin component stains osteoblasts, osteoclasts etc.

Answer 23

Goldners Trichome stains

Question 24

Use of basic dye.
Stains rough endoplasmic reticulum found in neurones.
When seen as clumps, known as nissyl substance.

Answer 24

Nissily and Methylene Blue

Question 25

Stains lipid-containing structures – myelin.
Brownish-black colour for light microscopy.

Osmium also provides contrast in electron microscopy.
Electron dense structures are those with an affinity for osmium staining.

Answer 25

Sudan black and osmium