An immunocytochemical method for studying patterns of cell proliferation in the wool follicle

The identification of cell proliferation sites in the wool follicle bulbs of the skin of New Zealand Romney sheep was investigated with two immunocytochemical techniques. These methods were based on the in vivo labelling of DNA synthesising follicle matrix cells with the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU) and a surgical preparation of the skin on the lateral abdominal flank of the sheep. Using a monoclonal antibody to BrdU, an indirect immunoenzyme method and a biotin-streptavidin method were compared for specificity and sensitivity in detecting replicating bulb matrix cells which had incorporated infused BrdU during the S-phase of the cell cycle. The immunocytochemical results for both methods showed a black-brown staining reaction of cell nuclei entering mitosis. The biotin-streptavidin method proved to be more highly specific and sensitive than the immunoenzyme technique. The immunocytochemical detection of cell cycle S-phase is highly suited for studying cell proliferation sites and cytokinetics in wool follicle bulbs and in other mitotically active tissues. Immunocytochemical detection of mitotically active cells has the advantages of high specificity, cost efficiency and rapidity and may be an alternative to methods employing metaphase arresting agents like colchicine or autoradiography.