Intro to Hist

Question 1

What are the steps involved in Microscopy?

Answer 1

Remember: The Fly Does Eat, Sans Mouth Villi

Tissue collection, Fixation, Dehydration, Embedding, Sectioning, Mounting and Staining, Viewing

Question 2

What are 3 types of tissue collection?

Answer 2

Needle biopsy, Endoscopic biopsy, Other (Transvascular, Direct Excision, Curettage)

Question 3

What is a cutterage biopsy?

Answer 3

removal of tissue by scooping or scraping, ex: endometrial lining of uterus

Question 4

What is the goal of fixation and why is dehydration only relatively good at fixating?

Answer 4

prevent degradation + maintain architecture. Dehydrating = no fine detail

Question 5

What are some common CHEMICAL fixatives?

Answer 5

Formaldehyde (crosslinks proteins and inactivates them) and Glutaraldehyde

Question 6

What is one dehydration fixative?

Answer 6

OH

Question 7

What can you use to rapid freeze for fixation?

Answer 7

Liquid isopentane OR N2

Question 8

What methods/materials can be used for Embedding and sectioning?

Answer 8

Paraffin wax, Acrylic resin, Frozen sections

Question 9

You have a sample that is 6 µm wide. What embedding material would you use?

Answer 9

Paraffin wax, best for 5-8 µm for light microscopy, Good resolution but slow (24 hrs)

Question 10

What would you use for a 1 µm section that is to be used in high res light microscopy. What Embedding agent should you use?

Answer 10

Acrylic Resin, make it hard, bake it, ultrathin EM (60-80 µm), incompatible with most stains, slow!

Question 11

What embedding agent is used when rapid-freezing?

Answer 11

Water! 12-20 µm, so low res, IDEAL for most stains, RAPID

Question 12

H & E Stain?

Answer 12

Hematoxylin is Blue= Basic binds to Acid (cartilage matrix)

Eosin is Pink= Acidic, binds to basic regions (collagen fibers)

Question 13

Massons’s trichome?

Answer 13

Dark Blue: Nuclei
Red: Muscle, keratin, cytoplasm
Light Blue: mucinogen, collagen

Question 14

I want to view an RBC under a microscope, what should I use?

Answer 14

RBC is 7.6 µm, so use Light Microscope (0.25 µm)

Question 15

I want to look at a human ovum, what should I use?

Answer 15

Human ovum is 100 µm, so use Light Microscope (0.25 µm)

Question 16

I want to look at some S. Aureus. What should I use?

Answer 16

Staph is 1 µm, so use Light Microscope (0.25 µm)

Question 17

I want to look at a virus like Polio, what should I use?

Answer 17

Polio is 28 nm so use Scanning Electron Microscope (SEM) (10 nm)

Question 18

Histological sections are _ dimensional views of _ dimensional structures.

Answer 18

2, 3

Question 19

What are the types of cuts of a histological section?

Answer 19

oblique sections, longitudinal section, cross-section

Question 20

What does H & E highlight?

Answer 20

Hematoxylin, H, Blue, acidic, binds to cartilage matrix

Eosin, E, Pink, Basic, Collagen fibers

Question 21

What do you see under scope of Connective Tissue with H & E stain?

Answer 21

Histiocyte (Macrophage), Blue
RBCs, Red or Pink (7.6 µm)
Collagen, Pink stringy

Question 22

What do you see with blood on Wright stain?

Answer 22

Basophils- Red inner material

Question 23

What is a Wright Stain?

Answer 23

Methylene Blude and Eosin, used for differential staining of blood cells.
Pink- RBCs, Eosinophil granules
Blue- Nuclei of WBCs, cytoplasm of monocytes and lymphocytes