BrdUrd labeling of S-phase cells in testes and small intestine of mice, using microwave irradiation for immunogold-silver staining: an immunocytochemical study.

In this study, BrdUrd labeling of S-phase cells in the small intestine and testes was accomplished using microwave irradiation. In this way crypt cells, spermatogonia, and Leydig cells could be labeled using removable plastic-embedded sections and immunogold-silver staining (IGSS). By using short periods of microwave irradiation for incubation of the monoclonal antibodies and the protein A-colloidal gold solution, the detection of BrdUrd-labeled cells could be remarkably enhanced. A comparative study of BrdUrd labeled spermatogonia in the testis of a Cpb-N mouse that received both [3H]-thymidine and BrdUrd proved that 90% of the BrdUrd-labeled cells also showed [3H]-thymidine labeling. The radioactive [3H]-thymidine labeling was a time-consuming method of 4 weeks' duration, whereas the BrdUrd-labeled cells could be labeled, fixed, enhanced, and counterstained in less than 3 hr. This investigation proves that BrdUrd labeling of S-phase cells can be a reliable, reproductive, rapid, and non-radioactive alternative method for [3H]-thymidine labeling of proliferating cells.