4. Histochemistry. Methods of demonstartion of carbohydrates, lipids and proteins.

Question 1

Cell differentiation definition?

Answer 1

Process used to separate cellular components and a process in which cells develop into their specialised functions

Question 2

MOD of Carbohydrates?

Answer 2

• Demonstrated by the PAS reaction
• PAS Reaction: Periodic Acid Schiff
  •Bring sections to distilled water.
  •Treat with periodic acid for 5 minutes.
  •Rinse well in distilled water.
  •Cover with Schiff’s reagent for 5-15 minutes.
  •Wash in running tap water for 5-10 minutes
  •Counter stain with Herri’s hematoxylin for approximately 15 seconds.
  •Differentiate (if necessary) with acid alcohol and bluing as usual.
  •Wash in tap water.
  •Rinse in increasing concentration of alcohol (70, 80, 95 and 100%)
  •Clear in xylene and mount as usual.

PAS stain is mainly used to highlight the molecules (structures) with high percentage of carbohydrate content such as:

• Glycogen
• Glycoproteins
• Proteoglycans

Typically found in:

• Connective tissue
• Glycocalyx
• Basal laminae.

Question 3

Staining results for carbohydrates? PAS?

Answer 3

-Rose to Purple reaction:
•Glycogen, mucin, reticulum, colloid droplets, hyaline deposits in glomeruli, most basement membranes, colloid of pituitary stalks and thyroid

-Red
•Fungi

-Blue
•Nuclei

Question 4

MOD of Lipids?

Answer 4

• Best revealed with dyes that are soluble in lipids
• Sudan IV and Sudan Black are most commonly used
• Sudan 3 as well

Question 5

MOD of Proteins?

Answer 5

Alcian Blue