Cytology II: Histology

Question 1

Histology definition

Answer 1

Study of tissues

Question 2

Histopathology definition

Answer 2

The study of the disease of tissues

Question 3

Tissue definition

Answer 3

An aggregation of cells and intercellular materials specialized for specific functions

Question 4

___ are always part of a tissue. Tissue’s function determines what cells are ___. ___ make tissue function possible. Structure of cells often predictable based on tissue ___ & vice versa.

Answer 4

1. Cells
2. Present
3. Cells
4. Function

Question 5

What are the four tissue types

Answer 5

1. Epithelial
2. Connective
3. Muscle
4. Neural

Question 6

Epithelial tissue
Location:
Classified by…
Types: (3)

Answer 6

1. Location:
   - All body surfaces inside & out
2. Classified:
   - Layering style & cell type
3. Cell types:
   - Squamous
   - Cuboidal
   - Columnar

Question 7

Connective tissue
Location (6)
Function

Answer 7

1. Located throughout the body
   - Ligaments
   - Tendons
   - Dermis
   - Adipose (fat)
   - Cartilage
   - Bone
2. Function
   - Connects structures and provides structural support

Question 8

Muscle tissue
Function
Types (3)

Answer 8

1. Function
   - Ability to relax & contract
2. Types:
   - Smooth muscle: unconscious movement (no stripes)
   - Skeletal muscle: conscious movement (stripes)
   - Cardiac muscle: unconscious movement (stripes)

Question 9

Neural tissue
Function
Locations (3)

Answer 9

1. Function
   - Ability to conduct electric & electrochemical signals
2. Locations
   - Brain
   - Spinal cord
   - Peripheral nerves

Question 10

Organs definition

Answer 10

Aggregations of cells, tissues, and intercellular materials specialized for specific functions

Question 11

Histology tissue samples are evaluated to… (3)

Answer 11

1. Determine normal physiology
2. Diagnose disease
3. Understand pathophysiology of disease

Question 12

Punch biopsy

Answer 12

Used to take sample of skin. Designed to obtain full skin thickness.

Question 13

Bone marrow biopsy

Answer 13

1. Site is sterilely prepared
2. Bone marrow needle is rotated into bone until solidly seated
3. Stylet is then removed and the needle is rotated further
4. Instrument angle is changed several times in attempt to cut off sample of bone & marrow
5. Entire instrument is removed at once and the stylet is used to push the biopsy sample from the needle core
6. Sample is submitted in formalin. Bone will need to be decalcified before histology samples can be prepared & interpreted

Question 14

TruCut Biopsy
How it works: (4)

Answer 14

1. A needle with a gap near its tip is passed into the lesion.
2. A surrounding sheath with a cutting tip is passed down the needle.
3. The sheath cuts a specimen corresponding to the gap in the needle.
4. The needle and sheath, with the specimen, are then removed from the patient.

Question 15

Endoscopic biopsy
How it works: (4)

Answer 15

1. Biopsy samples are collected with a mucosal biopsy instrument.
2. Instrument is designed to collect a shallow sample and not perforate the hollow organ.
3. Sample is placed on balsa wood or cassette with 22G needle.
4. Rapidly placed in formalin to prevent drying of these very small samples.

Question 16

Surgical biopsies
Incisional vs Excisional

Answer 16

1. Incisional
   - Surgical cut into an organ or tumor.
   - Wedge sample typically collected to minimize bleeding and make closure simple.
2. Excisional
   - Complete removal of a tumor or abnormal organ/organ section.
   - Procedures are usually intended to be therapeutic as well as diagnostic.

Question 17

How should a biopsy be handled immediately after collection?

Answer 17

Preserved as indicated ASAP after collection!!
- Formalin
- Culture media
- Frozen
If allowed to dehydrate, sample will rapidly lose info & can become worthless for diagnosis.

Question 18

Biopsy handling: Fixation
It is important to fix fresh samples in __% neutral buffered ___ and placed in a plastic container of suitable size with a wide ___ and a ___ fitting lid. Narrow ___ are avoided as it is difficult to remove/place sample in it.
A ___mL container is ideal for most samples.

Answer 18

1. 10%
2. Formalin
3. Neck
4. Tight
5. Necks
6. 100mL

Question 19

T/F: Ideal amount of fixative for a 2x1x1cm tissue should be placed in a container with about 100-150mL of fixative.

Answer 19

False! It should be about 50-60mL for a 2x1x1cm tissue sample

Question 20

With larger samples, how much fixative is generally recommended? What else can be done with a larger sample?

Answer 20

1. 10x the volume of the sample
2. Since the center may not get fixed, it may be best to only take a portion of the sample

Question 21

___, ___, & ___ should be submitted whole and intact, in adequate fixative as indicated.
This will allow assessment of excision margins meaning if the animal was ___ or not.
Be certain to include ___ tissue with the sample!

Answer 21

1. Skin
2. Tumors
3. Masses
4. Cured
5. Normal

Question 22

Samples should be placed in ___ bags. Forms should be ___ filled including the ___ of sample and patient ___. This is especially important with ___ samples!

Answer 22

1. Polythene
2. Completely
3. Location
4. History
5. Skin

Question 23

In the lab, bone samples are decalcified with __% ___ acid to remove ___ content. They may be left in this for ___ until chemical test for calcium is negative.
After this, embedding will be done. This is done by a bed of ___ poured over the sample. Once ___ the sample is cut into transparent slices by a microtome.

Answer 23

1. 10%
2. Calcium
3. Weeks
4. Wax
5. Hardened

Question 24

What does the lab routinely stain the sample with? (2)

Answer 24

Haematoxylin & Eosin (H & E)

Question 25

Viral inclusions are stained with...

Answer 25

Phloxine tartrazine

Question 26

Stain used for mast cells...

Answer 26

Toluidine blue

Question 27

Stain used for amyloid samples is...

Answer 27

Congo red - Apple-green birefringence under polarized light