Strain differences in the ovulatory response of immature mice to PMS and to the pheromonal facilitation of PMS-induced ovulation.

Pheromonal facilitation of PMS-induced ovulation was compared in six strains of immature mice following exposure to adult males of the same strain. All mice were injected with PMS at 24 days of age and exposed to adult males 51 hr later. Examination of the animals for ovulation was carried out at 72-74 hr after the PMS injection. Significant facilitation of average number of ova released and/or percentage of mice ovulating was found for the BALB/cJ, SWR/J, and C3HeB/FeJ mice at both a dosage of 3 and 7 IU of PMS. The SJL/J strain showed facilitation at the 7 IU dose of PMS, but none at the 3 lU dose. The DBA/2J strain showed an inhibition at 3 1U PMS and facilitation at 7 lU while the C57BL/6J showed no facilitation at either 1, 3, or 7 IU of PMS but did so at S IU. It is apparent a significant strain difference exists both in the ovulatory response of mice to PMS and in the ovulatory response to the combined treatment of PMS and exposure to the adult male of the same strain.