Histology Primer

Question 1

What tissue is this?

Answer 1

• Skeletal Muscle
  
  • Cross-section
  • Looks polygonal

Question 2

What tissue is this?

Answer 2

• Skeletal Muscle
  
  • Longitudinal section
  • Looks elongated

Question 3

What tissue is this?

Answer 3

• Stratified squamous epithelium
  
  • Above or cut thru top layer
  • Cells = polygonal

Question 4

What tissue is this?

Answer 4

• Stratified squamous epithelium
  
  • Surface cells = flattened or squamous

Question 5

What shaped cell do we see?

Answer 5

• Columnar
  
  • Rectangular
  • Nuclei = oval, closer to basal lamina

Question 6

What shape of cell do we see?

Answer 6

• Cuboidal
  
  • Square
  • Nuclei = round, centrally located

Question 7

What is in between the 2 lumen?

Answer 7

• Muscle

Question 8

What is bordering the basal lamina?

Answer 8

• Connective tissue

Question 9

What organ are these cells in?

Answer 9

• Pancreas
  
  • granules = zymogens

Question 10

What are these special cells?

Answer 10

• Neurons
  
  • Large nuclei
  • Prominent nucleoli
• Found in peripheral or CNS

Question 11

What staining do we use for light microscopy?

Answer 11

• Hematoxylin
  
  • Basic dye (Basophilic structures)
  • Stains acidic structures (anionic structures)
    
    • BLUE
    • ex: nucleus
  • Other basic dyes:
    
    • Toluidine blue
    • Methylene blue
• Eosin
  
  • Acidic dye (Acidophilic or eosinophilic structures)
  • Stains basic structures
    
    • PINK
    • ex: proteins/cytoplasm

Question 12

How to Approach a Slide?

Answer 12

1. Is there more than one tissue type? Then it is an organ
2. Look at magnification & cut (as for tissues)
3. Look for a lumen – epithelium lines a lumen
   
   • ID the epithelium
     
     • this is the most important clue as that what the section is
   • Look deep to the epithelium
     
     • connective tissue is found deep to epithelium
   • ID type of CT
     
     • Look deep to the CT – often there is muscle
       
       • check type of muscle

Question 13

What type of staining is this?

Answer 13

• PAS staining
  
  • Acute Lymphoblastic Leukemia
  • Bone marrow biopsy
• Detects things w/ carbohydrates (ie: glycoproteins)

Question 14

What type of staining is this?

Answer 14

• Prussian blue
  
  • Hemochromacytosis
  • Liver Biopsy
• Detects things w/ lots of iron

Question 15

What is this?

Answer 15

• Myotubes
  
  • Glycogen is lost during processing

Question 16

What type of tissue is this & what stains are used?

Answer 16

LEFT

• Simple columnar epithelium
  
  • H & E
  • mucin lost

RIGHT

• Simple columnar epithelium
  
  • PAS
  • mucin preserved

Question 17

What are the 7 types of special stains?

Answer 17

1. PAS
   
   • Carbohydrates
   • used diagnostically for glycogenolysis & mucopolysaccharidosis
2. Wright’s stain
   
   • Blood
   • Eosin & methylene blue
3. Elastic tissue/elastic fibers
   
   • stain pink or black
4. Osmium
   
   • Lipids
5. Sudan black
   
   • Lipid soluble dye
   • detection of sphingolipids
6. Silver stains
   
   • Golgi/reticular fibers = black
7. Prussian blue
   
   • Iron = blue

Question 18

What is Metachromasia?

Answer 18

• Metachromatic dyes = everything one color (blue)
  
  • stain specific structures (purple) due to chemistry
• Example:
  
  • toluidine blue = stains BLUE
    
    • tissues w/ high [sulfur] = PURPLE
      
      • structures w/ glycoaminoglycans (GAGs)/proteoglycans (PGs)

Question 19

How does Enzyme Histochemistry work?

Answer 19

• Uses the fxn of the enzyme
  
  • give a substrate & generate a rxn product
• Acid phosphatase histochemistry
  
  • black = reaction product

Examples:

• Acid phosphatase w/in lysozymes in kidney tubule cells (TEM)
  
  • apical surface

Question 20

What are the 3 types of Immunochemistry?

Answer 20

1. Immunocytochemistry = CELLS
   
   • Ab against intermediate filaments
   • 2° Ab = fluorescent
2. Immunohistochemistry = TISSUES
   
   • ​ Ab against lysozyme + 2° Ab
   • Yields brown rxn product
     
     • helps ID location of lysozyme
3. In Situ Hybridization
   
   • Strand of nucleic acid = probe
     
     • bind to complementary sequence
   • visualize via brown rxn or fluorescence
     
     • ex: HPV