BrdU （5-bromo-2'-deoxyuridine） is a thymidine analog that can be incorporated into newly synthesized DNA strands during DNA replication, used to detect cell proliferation. BrdU antibodies are monoclonal or polyclonal antibodies that specifically recognize BrdU-labeled DNA and are widely used in experiments such as immunohistochemistry and flow cytometry to visualize or quantitatively analyze proliferating cells.