revision:

• 10% buffered formalin is he msot common used fixative

why do we fix?

• prevent autolysis (enzyem destruction of the tissue) → disintegration of the cell
• prevent putrifaction → growth of bacteria and fungi (usually from the alimentary cancal + skin)

fixative should allow the cell and tissue to be stained (formalin is good in this case)

• special cases like immunohistochemistry too + others

top 3 features of 10% neutral buffered formalin

major disadvantage:

• carcinogenic

• extraction of dna/rna is diffcult after fixing with formalin

other fixative

• glutardehyde is commonly used for e-microscope
  • mainly to prseve proteins (amino acids)

features affecting fixation:

• pentetation