This digoxigenin-labeled oligonucleotide probe recognizes Alu repetitive sequences present within the mammalian genome (1-2). Specific hybridization of this probe to human Alu in FFPE tissues indicates that the test material contains intact DNA. This probe is to be used as a control when running specific DNA targeting probes. Weak or light staining in a test sample indicates that specifically targeted DNA may be compromised.
The in situ hybridization technique offers an important advantage over immunohistochemistry, as it virtually lacks background, and allows a clean and sharp viewing of the histological preparation.