Department of Agricultural Science, University of Oxford, Parks Road, Oxford
(Received 29th November 1974)
Although members of the species Microtus agrestis are induced ovulators (Austin, 1957; Breed, 1967), ovulation may be induced by stimuli other than those associated with mating, e.g. when females are separated from adult males by wire mesh (Milligan, 1974). Tactile contact between the sexes is not necessary for this ovulatory response as ovulation still occurred when two barriers of mesh, 2·5 cm apart, separated the male and female (Milligan, 1974). The present experiments continued the investigation of the nature of the effective stimuli for ovulation which are provided by non-coital contact with a male.
Laboratory bred voles from the `mixed-type' colony described by Milligan (1974) were used. Males were fertile adults from the breeding colony; all females had shown cornified vaginal smears on 3 consecutive days before the experiments. In Exp. 1, virgin females were treated