The fate of epidermal colcemid-arrested mitoses.

This study reports the fate of hairless mouse epidermal basal cells arrested in mitosis by a traditional stathmokinetic dose of 0.15 mg Colcemid. Epidermal basal cells in the S phase were labeled with 30 microCi (3H)TdR i.p. After 1 h, four animals from a cage of eight mice were given 0.15 mg Colcemid (Fluka) in 0.5 ml saline, and the other four mice were given saline only. Groups of eight mice (four experimental, four controls) were sacrificed 4, 9, 13, 21 and 25 h after (3H)TdR injection (i.e. 3, 8, 12, 16, 20 and 24 h after Colcemid). The following cell kinetic parameters were determined: the number of labeled basal and suprabasal cells, the mean grain count of the labeled cells, the specific activity, the mitotic count, the number of labeled mitoses, the fraction of labeled mitoses curve and the fraction of cells in S and in G2 as determined by flow cytometry. "Labeled paired twins", i.e. adjoining labeled cells with approximately the same grain count, were also scored. All the results taken together support the conclusion that cells labeled with (3H)TdR and arrested 1 h later with 0.15 mg Colcemid go through at least one subsequent cell division and thereafter some of them move out into the suprabasal layer at a normal rate. Hence, after this dose of Colcemid, cells arrested in mitosis for some hours do not die, and the Colcemid treatment does not seem to produce hyperploid cells. The study confirms the usefulness of this dose of Colcemid as a convenient tool for cell kinetic studies.