Sexing mouse pups.

Data on the early sexing of random-bred albino mice (Mus musculus) is presented. It is shown that accurate sexing of newborn pups cannot be made by anogenital distance measurement unless the proportion of animals falling into the overlap-zones are discarded. However, 8-day-old pups may be sexed by the display of abdominal (inguinal) teats in the females.