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KMID : 0378019740170020198
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New Medical Journal
1974 Volume.17 No. 2 p.198 ~ p.208
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Abstract
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On the study of cell proliferation, ´H-thymidine has been widely used for the purpose of labelling cells in which DNA is synthesized with the assumption that ´H-thymidine is available for lesser than one hour following injection, and that those cells which enter the DNA synthesis phase, i. e. S-phase, are not labelled after an hour elapsed.
In the present work, the percentage of labelled nuclei is several cell populations was estimated in mice and one day postnatal chicks at given time following injection of 3H-thymidine.
The percentage of radioactive nuclei, referred to as "labelling index´ was determined by counting labelled as well as unlabelled nuclei. This was done under oil immersion in continuous square fields and autoradiographs were exposed for the adequate dates.
The figure for each table, 1 to 5, represents the count of at least 3, 000 nuclei except for myocardial cells where usually fewer nuclei were available to be counted.
The results obtained were as follows:
1. Labelling index of duodenal cryptal cell in the 17th day of gestation mice was highest among the experimented cell populations.
2. In general, labelling indices of cell populations of 20 day old mice were lower than those of 17th day of gestation mice.
3. In the liver cell of one day postnatal chick, the labelling index showed significantly higher in PM 3 group than in AM 6.
4. Duodenal cryptal cell of one day postnatal chick showed significantly higher labelling indices in AM 6 group than in PM 3, and as shown in figure 3 the graphic curves formed a bimodal distribution.
5. As time elapsed, labelling is expected to be increased, unexpectedly, however, at 3hr following ´H-thymidine injection labelling index was decreased: this is considered as the result of increasing mitosis.
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