Introduction to Histology

Question 0

What are transvascular biopsies used on?

Answer 0

• Heart
• Liver

Vascular = Blood flow, organs that have a lot of blood flowing through them

Question 1

What are the 7 steps of microscopy?

Answer 1

• Tissue collection
• Fixation
• Dehydration and clearing
• Embedding
• Sectioning
• Mounting and staining
• Viewing

Question 2

What are direct excision biopsies used on?

Answer 2

• Skin
• Larynx
• Uterine cervix
• Mouth

SLUM

Question 3

What is the curettage biopsy used on?

Answer 3

• Endometrial lining of uterus (scraping)

Question 4

Where is the endoscopic biopsy used?

Answer 4

• Respiratory tract
• Allmentary tract
• Urinary tract

Before endoscope you ask, Are(Allementary) You(Urinary) Ready(Respiratory)?

Question 5

What is the goal of fixation?

Answer 5

To preserve tissues by preventing degradation while maintaining normal tissue architecture.

Question 6

What are the three common fixative types?

Answer 6

• Chemical fixatives
• Dehydration
• Rapid freezing

Question 7

Why would you use glutaraldehyde over formaldehyde?

Answer 7

Glutaraldehyde is a stronger fixative and must be used for the slide to be compatible with an electron microscope.

GEM:
Glutaraldehyde
Electron
Microscope

Question 8

What are the three ways to embed and section?

Answer 8

• Paraffin wax
• Acrylic resin
• Frozen sections

FAP

Question 9

Paraffin Wax:
Thickness of slide?
Resolution?
Time?

Answer 9

• 5-8 um for light microscopy
• Good resolution of cell structure and tissue architecture
• Slow, 24 hours

Question 10

Acrylic Resin

• Thickness and microscopy type? (2)
• Incompatible with _________.
• Time?

Answer 10

• 1 um for high resolution light microscopy
• 60 - 80 nm for EM
• Histological stains
• Slow, several days

Question 11

Frozen sections
Thickness and visualization?
Ideal for ________ and __________ stains.
Time?

Answer 11

• Thick (12 - 20 um)m relatively low resolution
• Histochemical and immunological
• Rapid (minutes - hours)

Question 12

What is the hematoxylin stain used for? *

Answer 12

• Acidic structures in cell
• Cartilage matrix

HAC

Question 13

What is the eosin stain used for?

Answer 13

• Basic regions of cytoplasm

- Collagen fibers

Question 14

What is the Masson’s trichrome stain used for?

Answer 14

• Nuclei
• Muscle, keratin, cytoplasm
• Mucinogen, collagen

Question 15

What is Weiget’s elastic stain for?

Answer 15

• Elastic fibers

Question 16

What is the silver stain used for?

Answer 16

• Neurofilaments
• Reticular fibers

Silver is expensive and valuable. Neuro = brain, your brain is valuable.

Question 17

What is iron hematoxylin used to stain?

Answer 17

• Striations of muscle
• Nuclei
• Erythrocytes

Iron is in blood, erythrocytes in blood.
Need iron for muscles.

Question 18

What is the periodic acid-schiff stain used for? *

Answer 18

• Glycogen and carbohydrate rich molecules

Question 19

What is the Wright stain used to stain? *

Answer 19

• Used for differential staining of blood cells.
• Pink = erythrocytes
• Blue = nuclei of white blood cells, cytoplasm of monocytes and lymphocytes

Question 20

Resolution of:
Human eye?
Light microcope?
Transmission electron microscope?
Scanning electron microscope?

Answer 20

• 0.1 - 0.2 mm
• 0.25 um
• 0.2 nm
• 10 nm

Question 21

What is resolving power?

Answer 21

The ability of something to distinguish between two points as the two points come closer. This is the most important part of the microscope.

Question 22

What is autoradiography?

Answer 22

The incorporation of radioactive isotopes into macromolecules, which are then visualized by use of an overlay of film emulsion.

Black dots/ silver stains

Question 23

What is an enzyme histochemistry stain?

Answer 23

Cleavage of artificial substrate results in deposition of insoluble colored reaction product at site of enzyme activity.

Lots of dark dots.

Question 24

What is immunocytochemistry?

Answer 24

Binding of labelled antibodies enables visualization of macromolecules.

Direct and indirect

Question 25

How does transmission electron microscopy work?

Answer 25

Stain with heavy metal and look at the contrast. Metals include uranyl acetate and lead citrate.

Question 26

How do scanning electron microscopes work?

Answer 26

Generated by analyzing the pattern of electrons reflected from a thin layer of heavy metal (gold, palladium) deposited on the surface of the specimen. You get a 3D image.