H And E Staining

Question 1

Why are dyes coloured?

Answer 1

Dyes are coloured because there chemical structures absorbs some of the light wavelengths out of the white light spectrum.

Question 2

Fluorescence

Answer 2

The emission of light by a molecule following absorption of UV

Question 3

Factors affecting staining

Answer 3

• pH
• concentration of inorganic salt
• electrolyte concentration
• rates of reaction

Question 4

Progressive staining

Answer 4

The dye is left on for just the right amount of time to stain the particular molecule. If longer time period occurs, then nuclei and RNA- rich cytoplasm will also stain.

Question 5

Regressive staining

Answer 5

The tissue is overstained so even when there are weak interactions between tissue and dyes you get staining. The dye is washed using differentiation using buffers.

Question 6

Affects of pH on staining

Answer 6

Acid/ base solutions affect dye/ target molecule interactions. pH can also be used to selectively wash out dyes- differentiation.

Question 7

Affects of size on staining

Answer 7

Different sizes of stains will diffuse at different speeds.

Question 8

Differentiation

Answer 8

Differentiation of regressive staining involving selective loss of stain from tissue is commonly used.

Question 9

Metachromasia

Answer 9

The property of various tissues of staining in a different colour (as when treatment with blue aniline dye makes a cellular element red)

Question 10

Basophilic dyes

Answer 10

Describes the microscopic appearance of cells and tissues after a histological section has been stained with a basic dye attracted to basic molecules in the cell (DNA). E.g haematoxylin. (-ve charged)

Question 11

Acidophile

Answer 11

Describes particular staining pattern of cells and tissues when using haematoxylin and eosin stains. Acidophilic substances are +ve charged.