title: Study of the thymocyte cell cycle by bivariate analysis of incorporated bromodeoxyuridine and DNA content.
abstract: The in vivo cell cycle of normal murine thymocytes was studied by bivariate analysis of bromodeoxyuridine and total DNA content in the 24 h following a single injection of the thymidine analogue. Bromodeoxyuridine incorporation was strictly limited to cells in S phase and 98% of S phase cells were labeled, demonstrating high efficiency and specificity. Cell-cycle parameters were determined by measuring the DNA content of bromodeoxyuridine-labeled cells, related to their distribution in the different phases. The changes of this distribution as a function of time reflected the progression of the cells along the cell cycle. The duration of total cycle, S phase, and both G2/M and G1 was 10 h, 6.5 h and 1.5 h, respectively. All thymocytes labeled in S phase entered G2/M, divided and returned to the G0/G1. Seventy percent of them remained in the resting state, and the other 30% re-entered a second S phase. Cell-cycle parameters of isolated CD4-CD8- cells were also determined. No evidence of cell loss during S or G2/M phase was found, suggesting that intrathymic cell death is not directly linked to the proliferative phases of differentiation.
authors.affiliation: Immunologie Clinique, INSERM U25, CNRS UA22, Hôpital Necker, Paris.
authors.forename: C
authors.initials: C
authors.lastname: Baron
authors.forename: C
authors.initials: C
authors.lastname: Pénit
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D002455:Cell Division; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis; D005434:Flow Cytometry / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D015999:Multivariate Analysis; D010641:Phenotype; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D000911:Antibodies, Monoclonal; D004247:DNA; D001973:Bromodeoxyuridine