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KMID : 0351619750160010185
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Kyungpook Medical Journal
1975 Volume.16 No. 1 p.185 ~ p.192
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Study of the Cell Cycle and Circadian Rhythmicity of Esopageal Epithelial Cell in One Day Postnatal Male Chicks
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Abstract
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Most studies on various tissues of cell cycle are done at a -time of day that is convenient for the investigator, not the animal: yet, during cell cycle studies in cur laboratory, a significant variation has been noted in labeled mitotic figures according to the injection time of 1H-thymidine and time difference the sacrifice of animals with a 34-hour period.
The purpose of the present investigation was, firstly, to find out if there are diurnal variations in the number of DMA-synthesizing cells at the different injection times, occuring midway through the dark phase of a 13-13 light-dark cycle-a lighting regimen not too different from that used in .´many research vivariums; secondly, to see if there. are any :influences on cell cycle due to randomly set up 3H-thymidine injection times and sacrifice times.
One day postnatal male chicks were divided into four experimental groups, and AM and PM t Sacrifice groups.
Of the injection groups, AEI chicks were treated intraper]itoneally with 3H-thymidine at 6:00 AM and Pll chicks at 3:00 P?a respectively, and at the beginning of every hour, 3 chicks wire sacrificed.
In the sacrifice groups, at the beginning of every hour, starting from 5:00 AbI and 2:00 PM, a three chicks were treated 3H-thymidine and all the chicks were sacrificed at 6:00 AM and 3:00 PM next day.
Each esophagus was removed and subjected to autoradiogrG.phy to determine the cell cycle and parameters. The results ~vere~summarized.
(1) Proliferation activity of esophageal epithelial cells revealed distinct circadian rhythmicity.
(2) Proliferation activity was predominant in the AM sacrii.`ice and PM injection groups.
(3) Labelling indices of the ANI and PM injection groups were 10.0 %and 21.8%. In the sacrificed teps, the labelling indices were 19.8% in the AM group and 11.2% in the PM group.
(4) The number of labelled cells were the highest at the 10 PM in injection groups and w highest at the 10 AM and 11 PM in the sacrifice A.M and PM groups respectively.
(5) The duration of S phase v-as 8.2 hours in the AM injection group and 10.3 hours in the ] injection groups. In the sacrificed groups there was no significant difference between AM and ] groups.
(6) The duration of Gz phase was 3.7 hours in the AM sacrifice group and 2.6 hours in the I sacrifice group. In the injection groups, there was no significant difference between AM and I groups.
(7) The duration of T~ was 82.0 hours in the AN.[ injection group and 40.3 hours in the I injection group. In the sacrifice groups, the duration of T~ was 40.0 hours in the A]1I group a 91.9 hours in the PM group.
(8) Mitoses could be found only in germinal and sFiinous layers and mitotic cells appeared to ha a tendency to be crowded in some areas.
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