Automation of in situ hybridization

The authors used automated DNA hybridization equipment, the Code-On (Instrumentation Laboratory, Lexington, MA), for more than 2 years to perform in situ hybridization in the clinical and research laboratory. For in situ hybridization for viral DNA in fixed, paraffin-embedded tissue, the Code-On produces results that are as sensitive as the manual method and with considerably greater ease. The procedure must be modified to fit the operating characteristics of the Code-On. The authors outline a procedure that emphasizes sensitivity, rather than speed. The automated procedure requires close technical attention, but the authors propose that it is considerably more efficient than the manual method. One technician can produce reliable results on as many as 60 slides a day. For in situ hybridization on cytogenetic preparations, the results are excellent, but the procedure is contorted and the probe use is increased. For these reasons the Code-On is not used for routine interphase cytogenetics. The Code-On is in routine use in the authors' pathology laboratory for performing in situ hybridization on formalin, B5, and Carnoy's fixed, paraffin-embedded specimens.