Practice question

In situ hybridization preserves spatial context by detecting nucleic acids within fixed cells or tissue sections. Labeled antisense RNA or DNA probes penetrate permeabilized cells and hybridize to endogenous mRNA targets, which are then visualized enzymatically or fluorescently, revealing tissue-specific and subcellular expression patterns. Northern blot, real-time PCR, and CGH all require RNA or DNA extraction, destroying morphology and precluding localization. Because developmental biology, neurobiology, and pathology rely on knowing which cells express a transcript, in situ methods uniquely enable direct RNA detection in intact biological architecture.