title: Endogenous circadian rhythm in the photoperiodic ovarian response of the subtropical sparrow, Passer domesticus.
abstract: Groups of photosensitive female house sparrows have been kept under night-interruption and intermittent light cycles for a period of 6 weeks. The night-interruption cycle consisted of a basic photophase of 6 h and 1 h photointerruption of the dark phase in the 24 h cycle at different points. Ovarian growth was stimulated under cycles in which photointerruption of the dark phase was made 10 h after the onset of basic photophase. The intermittent light cycles consisted of 2 L:2 D, 3 L:3 D, 4 L:4 D, 8 L:8 D and 12 L:12 D besides two control groups held on 7 L:17 D and 17 L:7 D. Ovarian response was observed only in 2 L:2 D, 3 L:3 D, 4 L:4 D, 12 L:12 D and 17 L:7 D cycles. The results of both the experiments are consistent with an avian external coincidence model and indicate that circadian rhythmicity is involved during the initiation of the female avian reproductive system.
authors.affiliation: Center of Advanced Study in Zoology, Banaras Hindu University, Varanasi, India.
authors.forename: G
authors.initials: G
authors.lastname: Ravikumar
authors.forename: P D
authors.initials: PD
authors.lastname: Tewary
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D008027:Light; D009929:Organ Size / Q000502:physiology; D010053:Ovary / Q000502:physiology*; D010507:Periodicity; D010775:Photic Stimulation; D012098:Reproduction / Q000502:physiology