Protocol to detect RNAs from tissue sections in mice using Y-branched probe in situ hybridization

Here, we describe a fluorescent in situ hybridization protocol named Yn-situ, standing for Y-branched probe in situ hybridization, to detect RNAs from mice tissue sections. We provide steps for the synthesis and quantification of preamplifier probe using nickase. We also detail the preparation of tissue section, probe hybridization, signal development using hybridization chain reaction (HCR), and quantification of the signals. This approach avoids the use of proprietary in situ hybridization techniques, therefore reducing costs. For complete details on the use and execution of this protocol, please refer to Wu et al. (2022).