title: Ultradian biorhythms of cell proliferation.
abstract: We studied circadian and ultradian rhythms of mitotic index of epithelial cells of the esophagus, intestine, and dorsal surface of the tongue, and thymocytes from mice maintained at normal and inverted light regimens. It was shown that in normal animals, the period of ultradian oscillations was shorter during the active circadian phase compared to the passive phase. Photoinversion changed the correlation between ultradian oscillations of the mitotic index and its circadian phases, which was differently pronounced in various tissues. Thus, changes in daily illumination serve as the time indicator for circadian rhythms of cell proliferation, but not for ultradian oscillations of mitotic activity.
authors.affiliation: Department of Biology, Medico-Biological Faculty of the Russian State Medical University, Moscow.
authors.forename: Yu A
authors.initials: YA
authors.lastname: Romanov
authors.forename: V V
authors.initials: VV
authors.lastname: Evstaf'ev
authors.forename: V P
authors.initials: VP
authors.lastname: Rybakov
authors.forename: O A
authors.initials: OA
authors.lastname: Irikov
mesh_terms: D000818:Animals; D002455:Cell Division; D002940:Circadian Rhythm; D004847:Epithelial Cells / Q000166:cytology; D004947:Esophagus / Q000166:cytology; D007421:Intestine, Small / Q000166:cytology; D007422:Intestines / Q000166:cytology; D008027:Light; D008297:Male; D051379:Mice; D008938:Mitosis; D013950:Thymus Gland / Q000166:cytology; D014059:Tongue / Q000166:cytology