The page below is a sample from the LabCE course Technical Competence in Paraffin-Based Fluorescence In Situ Hybridization (FISH). Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Standard Pre-treatment

The historical standard FISH method has been used in cytogenetics laboratories for many years. These methods have been adapted for FFPE tissues. The pre-treatment steps include the following:
To perform this standard pre-treatment portion of the assay, slides are incubated in 0.2 N hydrogen chloride (HCI) for 20 minutes and washed in deionized H2O for three minutes at room temperature. Slides are then washed in 2X saline-sodium citrate (SSC) buffer for three minutes at room temperature. Slides are incubated in 1 M sodium thiocyanate pretreatment solution at 80° C for 30 minutes. The temperature is CRITICAL. All solution temperatures should be measured with a National Institute of Standards and Technology (NIST) certified thermometer directly in the solution. Do NOT rely on the digital reading of the water bath. Slides are washed in deionized H2O for one minute, followed by washing in buffer 1 for five minutes and buffer 2 for five minutes.