In situ hybridization allows detection and localization of specific nucleic acid sequences directly within a cell or tissue. We present an in situ hybridization protocol using double-stranded DNA or single-stranded RNA probes labeled with [32P] to localize and visualize the temporal and spatial distribution of cartilage-characteristic mRNAs. Probes labeled with this high-energy isotope provide good resolution at the tissue level with relatively low background; as a result of the probes that can be obtained that have a higher specificity to emulsion activity, very short exposure times are required.