Determination of oestrous condition in female mice is dependent upon time of day.
Mice were maintained in rooms with constant ambient conditions and a 12 h light:12 h dark daily light regimen with the lights on starting at 06:00 h. In Exp. I, detection of puberty, as measured by first vaginal oestrus, was recorded at significantly earlier ages when vaginal smears were taken at 04:00 or 08:00 h than at other times of the day. In Exp. II, adult females were detected as being in oestrus more frequently when vaginal smears were taken within 6 h before or after the onset of the light part of the cycle each day than at other times.
D000818:Animals; D001947:Breeding; D002940:Circadian Rhythm; D004972:Estrus Detection; D005260:Female; D051379:Mice / Q000502:physiology*; D008813:Mice, Inbred ICR; D012741:Sexual Maturation; D013048:Specimen Handling; D014626:Vaginal Smears