Fixation Options

10% Neutral Buffered Formalin

  • Routine fixative (Supplied free in our facility!)
  • Don’t use 10% formalin—this will destroy your data
  • Done at room temperature
  • Adequate for many antibodies (know before you fix!)
  • Not adequate for most lymphocyte markers
  • Fix no longer than 16-24 hours (for most samples—excluding bone), transfer to 70% EtOH for samples for IHC
  • Best to embed as soon as possible, but can stay in EtOH l

4% Paraformaldehyde (a buffered solution!)

  • Commonly used in perfusion protocols
  • Good for in situ hybridization (formalin works well, too)
  • More gentle and considered slightly better than formalin for IHC, FISH
  • Must be made just prior to use
  • Keep it a 4C

Zinc Formalin (a buffered solution!)

  • Commonly used for IHC when frozen not a good option
  • More gentle and considered slightly better than 10% neutral buffered formalin for IHC
  • Fix at room temperature

Bouin’s Solution (yellow)

  • Contains picric acid l
  • Maintains good morphology (good for brain)
  • Decalcifies bone while fixing tissue
  • May result in slight hardening of tissue if over-exposed (get into 70% EtOH within 48 hours)
  • Colors tissue and affects some histochemical stains

Frozen tissues

  • Freeze fresh or fixed tissues
  • Good for immunohistochemistry for problem antibodies
  • Decreased quality of morphology, better if pre-fixed
  • Not good for bone (can’t cut the tissue)
  • Store at -80
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