PAS Staining Practical

Question 1

Based on the results, which tissues / cell types contain Glycogen?

Answer 1

Hepatocytes in the liver

Question 2

How did you deduce which cell types contained Glycogen?

Answer 2

The +s reduced between the 1st and 2nd treatments

The diastase digested the glycogen in the 2nd treatment

Question 3

What is the role of Glycogen in the hepatocytes?

Answer 3

Storage of carbohydrates that can be converted to glucose when required

Question 4

Saliva can also be used in place of diastase in step 6 of the PAS procedure.

Why is this and what role does it play?

Answer 4

Saliva contains Amylase that can digest glycogen

Saliva initiates digestion in the mouth

Question 5

Which of the PAS positive cells in the Duodenum contain mucoproteins?

Answer 5

Glands of Brunner

Goblet Cells

Question 6

What is the role of the mucoproteins in the Glands of Brunner and Goblet Cells?

Answer 6

Glands of Brunner - Secretes alkaline mucus to protect epithelium of small intestine.

Goblet Cells - Lubricates food and protects the mucosa.

Question 7

Glycoproteins are found on the surface of cells and play the following roles…

Answer 7

Mediate cell interactions between extracellular matrix
Cell to cell adhesion
Cell recognition
Transportation

Question 8

Everything which stains magenta / pink poetics is a carbohydrate or carbohydrate complex.
True or false?

Answer 8

False (other molecules may already contain aldehyde groups PRIOR to treatment with PAS e.g. some amino acids!)

Question 9

How could the PAS staining procedure be modified to detect the presence of SCHIFF-POSITIVE material which is NOT a polysaccharide?

Answer 9

Omit the PA stage in the CONTROL slide: if it does stain, it means aldehyde was present in the original material.