Circadian mitotic rhythms in epithelial cells of human epidermis (Schevirg, 1959), rat cornea (Scheving,1967) and intestinal epithelium of the mouse (Sidgestad,1972) have been reported in the literature. It is the attempt of this investigation to determine the presence of a circadian rhythm governing the mitotic activity of hair follicle cells in neonatal white mice. The animals used were reared under closely controlled conditions of temperature, humidity, lighting and food. A total of forty-eight, three to four day old mice were used, with eight animals being sampled every four hours over a twenty-four hour period. Skin sections were removed and fixed in Bouins fluid. The tissues were dehydrated in alcohols, cleared in xylol and infiltrated and embedded in paraffin. The sectioned tissues were placed on glass slides, rehydrated and stained with hematoxylin and eosin. To assess the mitotic activity over the twenty-four hour period, cell counts within the follicles were made from the slides. For each animal, 1000 hair follicle cells were counted. Cells undergoing mitosis were identified and specific stages were tallied. These stages were 1) prophase, 2) metaphase, 3) anaphase-telophase and 4) unidentifiable cells. Photomicrographs were made to record the histology and demonstrate the mitotic activity.When the data was statistically analyzed, an analysis of variance test failed to show a significant difference among the mean values of dividing cells from animals sampled during the different time periods. However, the F value for metaphase favorably approaches the table F value for the conditions of this study.By far, the strongest data to support the existence of a circadian rhythm within the hair follicle cells of mice is demonstrated when the mean values for each of the mitotic cell categories are plotted against time for the twenty-four hour period. Metaphase shows peaks in activity at 6:00 a.m. and 10:00 p.m. A similar pattern is also seen for the unidentifiable cells. The peak mitotic activities for prophase, and anaphase-telophase was seen to occur at 10:00 p.m.
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/175790 |
| Date | 03 June 2011 |
| Creators | Dawn, Gary T. |
| Contributors | Ganion, Larry R. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | v, 61 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
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