In the ileum image, which technique is shown?

• A. In situ hybridization
• B. Immunolabeling on immunohistochemistry
• C. Western blot
• D. RT-PCR

Answer: (A)

Localization of gene expression within tissue sections is being demonstrated. In situ hybridization uses labeled nucleic acid probes that bind to the target RNA within fixed tissue, so the signal appears in specific cells or layers of the ileum while preserving the tissue’s architecture. This is what lets you see where a transcript is expressed directly in the tissue context.

Immunolabeling on immunohistochemistry would show where a protein is located using antibodies, typically revealing protein distribution rather than RNA. Western blot detects proteins in a tissue lysate as bands on a membrane, not within intact tissue structure. RT-PCR measures RNA levels after extracting RNA, producing amplification signals or bands, but it lacks spatial localization in tissue sections.