Effects of urine from pregnant and lactating female house mice on oestrous cycles of adult females.

It was demonstrated that mice treated with urine from pregnant or lactating females experienced longer periods of oestrus than did mice treated with water or urine from singly caged females. Application of urine by means of perforated capsules placed in the cage of the test mouse showed that the factor(s) responsible for the longer periods of oestrus was an airborne pheromone. The females experiencing longer oestrous periods ovulated (ova in oviducts), became pregnant and gave birth.