Effects of microwave pretreatment on immunocytochemical staining of vibratome sections and tissue blocks of human cerebral cortex stored in formaldehyde fixative for long periods.

The effects of the microwave antigen-retrieval method were investigated for five antibodies commonly used in neurosciences, i.e., Parvalbumin, Calbindin D28-K, MAP-2, MAP-5 and SMI-32. Immunocytochemical stainings were performed on free-floating vibratome sections of tissue which had been stored in fixative for as long as 10 months to compare the effects of microwave treatment in one of the different metal solutions or in distilled water. Microwave treatment of free-floating vibratome sections led to a severe wrinkling of the sections. Therefore the possibility of pretreatment of a thick tissue slice before vibratome sectioning was investigated. We conclude that microwave pretreatment of tissue slices in an aluminium chloride solution is the preferable antigen-retrieval procedure for the examined antibody staining when the immunocytochemical staining is lost or markedly reduced after storage in formaldehyde fixative for a long period. In particular SMI-32 and MAP-2, but also Parvalbumin staining, improved enormously after such a pretreatment.