In Situ Hybridization Histochemistry Using Alkaline Phosphatase-Labeled Oligodeoxynucleotide Probe

Recent progress in the field of molecular biology has provided a new method to localize an mRNA signal within a cell or tissue section. This technique, called “in situ hybridization histochemistry,” gives us dynamic information about gene expression at individual cellular lev- els. For the detection of a particular target mRNA, a specific probe that has complementary sequence to the target mRNA is used. This probe has to include a reporter molecules in order to visualize the position of the probe-mRNA hybrid on a tissue section (1 ). Conven- tional in situ hybridization procedures use radioisotopes (e.g., ³ H, ³⁵ S, ³² P) as reporter molecules that can be visualized by autoradiography after hybridization (2 –4 ). The use of autoradiography, both film auto- radiography and emulsion autoradiography, restricts the wide appli- cation of this method because of the following reasons.