Institut for Biomedicin

Lars Bolund

DNA synthesis in mouse epidermis - Labelled and unlabelled basal cells in S phase after administration of tritiated thymidine

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DOI

  • O. P.F. Clausen, Institute of Pathology, University of Oslo
  • ,
  • E. Thorud, University of Oslo
  • ,
  • L. Bolund

Epidermal basal cells were isolated from hairless mouse skin 30 min after i.p. administration of various activities of tritiated thymidine (3H-TdR). Smears were prepared for autoradiography and the proportion of labelled cells (LI) was determined after one, three and five weeks of exposure. Flow cytometric DNA measurements were made from the same cell suspensions and the proportion of cells with S phase DNA content was estimated. In some experiments the LI in three fractions sorted from the S phase was determined. The lowest activities of3H-TdR resulted in a significant discrepancy between the LI and the proportion of cells with S phase DNA content, and confirmed previous results. As the3H-TdR activity increased, so did both the number of heavily labelled cells and the LI, which approached the estimated proportion of cells with S phase DNA content. Autoradiography of sorted cells with S phase DNA content from normal epidermis showed that about 50%-60% of the cells in the middle of the S phase were labelled at an activity of about 1 μ Ci3H-TdR/g animal, and that about 80% were labelled at an activity of 4 μ Ci/g animal (the activity giving the maximal labelling index). In contrast, about 93% of the cells in the middle of the S phase were labelled in regenerating epidermis. Thus, there is in normal non-stimulated mouse epidermis a significant fraction of cells with S phase DNA content that escapes detection by3H-TdR autoradiography, but this fraction is decreased to a minimum during rapid regenerative proliferation.

OriginalsprogEngelsk
TidsskriftVirchows Archiv B Cell Pathology Including Molecular Pathology
Vol/bind34
Nummer1
Sider (fra-til)1-11
Antal sider11
ISSN0042-6431
DOI
StatusUdgivet - 1 dec. 1980

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