Module 4: Lipid Staining Flashcards
What main type of tissue is adipose tissue?
Connective tissue
What does adipose do?
Stores fat, pads organs, thermoregulation, is reserve energy supply
What are the two main types of fat and what do they do?
White fat - thermoregulation in adults
Brown fat - thermoregulation in newborns
Where does stored fat come from? (3)
Dietary fat as triglycerides in blood stream
Synthesized by liver and adipocytes by breaking down glycogen
When may lipids be present in stainable amounts?
Adipose tissue Degenerating cells Fat hydrolysis in disease Cholesterol Complex lipids in brain tissue in disease
What does adipose look like in a normal paraffin section?
Why?
Network of fibers and nuclei, fibrous connective tissue
Alcohol, xylene, and fat solvents remove the lipid during processing
How can fat be demonstrated?
Fat soluble dyes (oil red O)
Other stain methods (Nile blue, histochemical, immunohistochemical)
Polarized light (unique refraction)
Osmium tetroxide - blackens
What is the principle of fat soluble dyes like oil red O?
Selective/preferential solubility
Physical staining
What is selective/preferential solubility?
The dye is more soluble in the lipid than it is in its solvent
Lipid takes up the stain
How are sections made for oil red O?
Prepared frozen, fresh or fixed (formalin)
Usually cut at 10 microns
What is used to mount slides after staining for oil red O? Why?
Aqueous mounting media
Miscible with water
Resinous is miscible with xylene which destroys fat
What are the requirements for fat soluble dyes?
Highly colored
More soluble in fat than solvent
Not water soluble
Solvent must not remove fat
What are other stains that can demonstrate lipids?
Sudan III
Sudan IV
Sudan black B
What are the common solvents in fat soluble dyes?
Propylene/ethylene glycol Triethyl phosphate 70% alcohol 70% alcohol + acetone Isopropyl alcohol
Why are fat stains performed? What can they detect?
Fatty changes in tissue in disease or degradation (metabolic disorders, toxins like alcohol or organic solvents) Fatty emboli (bone fracture or crush injury) Liposarcoma
What is liposarcoma
Tumors arising from fat cells
What are the main reagents in oil red O?
Oil red O
Harris hematoxylin
Lithium carbonate
What are the results of an oil red O?
Blue nuclei
Red fat
Blue or gray background
What is a good control for oil red O?
Frozen section containing adipose
Why should fat stains be done in closed containers?
Evaporation will cause precipitation on the slides
Why would acid alcohol not be used to differentiate hematoxylin?
The alcohol would remove the fat
Why should slides not be blotted or pressed to remove coverslip air bubbles?
It will displace the fat droplets
Which of the following tissues would be acceptable forlipid demonstration?
a. paraffin of formalin fixed tissue
b. frozen of formalin fixed tissue
c. paraffin of Bouin’s fixed tissue
d. frozen of 70% alcohol stored
b. frozen section of formalin fixed tissue
Which fixative can be used to demonstrate lipids by blackening unsaturated bonds?
a. Bouin’s
b. Zenker’s
c. B-5
d. Osmium tetroxide
d. Osmium tetroxide
Which mounting media would be acceptable to use for cover slipping sections stained using oil red O?
a. Glycerin jelly
b. Canada Balsam
c. Permount
d. D.P.X
a. Glycerin jelly
What staining theory explains the ability of oil red O to demonstrate lipids?
a. adsorption
b. preferential solubility
c. covalent bonds
d. porosity
b. selective solubility
Which of the following solvents would be inappropriate for use when demonstrating fine fat droplets using oil red O?
a. isopropyl alcohol
b. propylene glycol
c. triethyl phosphate
d. ethylene glycol
a. isopropyl alcohol
List 4 criteria for preferentially soluble dyes
- Highly colored
- More soluble in substance to demonstrate than the solvent its dissolved in
- Not soluble in water
- Solvent does not destroy fat
List 4 commonly used preferentially soluble dyes
- oil red O
- Sudan III
- Sudan IV
- Sudan black B
Fatty changes in tissue occur in _______, _______ disorders that usually occur as a result of the introduction of _______; _______ or _______. The tissues that are commonly affected are _______, _______, _______
chronic metabolic
toxins, hypoxia, or diabetes
liver, kidney, and heart
Keep stain lids tightly closed to avoid evaporation of solvent which could lead to _______ on the section
precipitation
Sections stained for the demonstration of lipids should not be _______ or _______ to remove air bubbles as these will _______ droplets of lipids
blotted
pressed
displaced
