Are alcoholic fixatives suitable for immunohistochemistry?
Answer. Fixatives containing ethanol are generally not all that great for IHC. About 4-5 years ago we experimented with several fixatives in an attempt to find one that would give us the cellular morphology that we were used to and also be optimal for IHC/ICC. We tested out the following fixatives: 10% NBF 70% EtOH 70% MeOH Carnoy’s methacarn (Carnoy’s with methanol instead of ethanol) zinc formalin, unbuffered buffered zinc formalin The 10% NBF of course gave us the morphology we were used to, and if fixation times were kept to 24-48 hours, epitope retrieval was not required for most antibodies. If tissues needed to be stored longer than 48 hours, they were stored in 70% EtOH until ready to be processed. Of all the fixatives we tested, the worst for IHC was 70% EtOH, then Carnoy’s. The best for IHC was 70% MeOH. Cellular morphology for both of these was not all that great. Methacarn gave us both good morphology and good IHC. The zinc formalins gave excellent morphology in many organs,