DNA-synthesizing cells in oral epithelium have a range of cell cycle durations: evidence from double-labelling studies using tritiated thymidine and bromodeoxyuridine.
Mouse tongue epithelium is characterized by a circadian variation in the number of DNA-synthesizing cells (labelling index, LI). Cells undergoing DNA synthesis were labelled with tritiated thymidine [( 3H]TdR) at 0300 (peak LI) or 1200 h (low LI). The fate of these cells was assessed by injecting animals with bromodeoxyuridine (BrdU) at intervals from 12-48 h after [3H]TdR, to follow them from one cell cycle to the next. Labelling was revealed by combining [3H]TdR autoradiography with immunoperoxidase detection of BrdU in the same sections. A single peak in the appearance of double-labelled cells was seen at 44 h, if [3H]TdR was given at 1200 h; following [3H]TdR at 0300 h, a peak of double labelling was seen at 48 h with the possibility of smaller peaks at 24 h and 36 h. These results show that the 24 h periodicity in LI in this tissue is associated with a predominant cell cycle duration of 44-48 h, but that a few cells cycle more quickly. Double labelling with [3H]TdR and BrdU provides a useful method for establishing cell cycle duration by labelling S-phase cells in successive cell cycles.
Hume
W J
WJ
Department of Dental Surgery, Leeds University School of Dentistry.
D000818:Animals; D001345:Autoradiography / Q000379:methods; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D004247:DNA / Q000378:metabolism*; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism / Q000502:physiology; D007399:Interphase; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013936:Thymidine / Q000378:metabolism; D014059:Tongue / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D014316:Tritium / Q000378:metabolism
D014316:Tritium; D004247:DNA; D001973:Bromodeoxyuridine; D013936:Thymidine