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Labelling of Cells Engaged in DNA Synthesis: Autoradiography and BrdU Staining

  1. Peder Madsen

Published Online: 18 OCT 2010

DOI: 10.1002/9780470015902.a0002572.pub2



How to Cite

Madsen, P. 2010. Labelling of Cells Engaged in DNA Synthesis: Autoradiography and BrdU Staining. eLS. .

Author Information

  1. University of Aarhus, Aarhus, Denmark

Publication History

  1. Published Online: 18 OCT 2010


The cell cycle is divided in four phases: G1 phase, S phase (DNA-synthesis), G2 phase (together termed interphase) and M phase (mitosis). Cells that have ceased proliferation enter a state of quiescence called G0. M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's chromosomes are divided between the two daughter cells, and cytokinesis, in which the cell's cytoplasm divides in half forming distinct new cells. It is often necessary to evaluate the proportion of DNA-replicating nuclei (S-phase cells) in a given population of cells. Classical methods for detection of cells in the S phase use incorporation of modified nucleosides, followed by direct visualisation of the DNA -replicating cells.

Key Concepts:

  • Identification of actively DNA-replicating nuclei by incorporation of bromodeoxyuridine and detection by immunofluorescence using bromodeoxyuridine specific antibodies or by incorporation of [3H]thymidine and visualisation by autoradiography.

  • Labelling of S-phase cells by bromodeoxyuridine or [3H]thymidine is a direct method to asses the proliferative index of tissue cell cultures.

  • Cell cycle studies using the number of S-phase cells as index for cell proliferation are conveniently conducted by incorporation of bromodeoxyuridine or [3H]thymidine into nuclei engaged in DNA synthesis.

  • Bromodeoxyuridine and [3H]thymidine are both incorporated into DNA by eukaryotic DNA polymerases and are therefore valuable tools in studies of hyperproliferative cells as well as normal cells, thereby aiding to the understanding of the transition of normal cells to cancer cells.


  • cell cycle;
  • DNA replication;
  • cell proliferation;
  • S phase;
  • DNA synthesis;
  • bromodeoxyuridine (BrdU);
  • [3H]thymidine