Daylength and sexual maturation in female house mice.

A series of 4 experiments investigated the relationship between day length and sexual maturation in female house mice. Mice reared in constant light matured significantly later than mice maintained under photoperiods involving 0, 6, 12, or 18 hr of light/day. Results of an experiment involving cross-classified combinations of pre- and postweaning photoperiods revealed that only the postweaning photoperiod treatment was a significant factor influencing the attainment of puberty. Studies of body growth, food consumption, and wheel-running activity in young females housed under different photoperiods indicated that mice kept in constant light grew more slowly during the first 10 days after weaning, generally consumed more food than mice at other photoperiod conditions, and failed to exhibit regular daily activity patterns like those of mice maintained under photoperiods of 0 or 12 hr of light/day. Constant illumination apparently disrupts the normal physiological and behavioral activity rhythms and delays the attainment of sexual maturity.