Effect of period of grouping of donors and duration of stimulus exposure on delay of puberty in female mice by a urinary chemosignal from grouped females.

Females housed at a density of 8 mice/cage had to be grouped for a minimum of about 10 days before their urine was capable of producing delays for first vaginal oestrus in test females comparable to the delays occasioned by treatment with urine from females grouped for 30 days or longer. Young test females had to receive a minimum daily exposure of 1-2 h to the chemosignal to produce the complete delay of puberty.