DISRUPTION OF EARLY-PREGNANCY BY DIRECT AND INDIRECT EXPOSURE TO NOVEL MALES IN MICE - COMPARISON OF INFLUENCES OF PREPUTIALECTOMIZED AND INTACT MALES

Inseminated female CF-1 mice (Mus musculus) were exposed on days 1 to 5 of pregnancy to unfamiliar outbred males. In the first experiment, i nseminated females were each housed directly with the sire, a preputia lectomized male, or an intact male. Both types of novel male attempted to mate with the female during this period, unlike the sire. Reinsemi nation occurred in a significant proportion of the females that were e xposed to novel males; this effect was equivalent for preputialectomiz ed and intact males. In two subsequent experiments, we refined a parad igm of indirect exposure to novel males through a wire-mesh grid, whic h prevents mating and reinsemination. Two or three males housed direct ly above each female through a grid disrupt pregnancy in most cases, b ut housing the males below the females is much less likely to do so. I n a final experiment, each inseminated female was housed below two mal es that were either preputialectomized or sham-preputialectomized. Whe reas 29 of 33 undisturbed controls were parturient, only eight of 32 f emales exposed to sham-preputialectomized males and six of 32 exposed to preputialectomized males were parturient. These results suggest tha t nonvolatile pheromones are involved in novel-male-induced pregnancy disruptions, but that preputial gland emissions are not necessary for such disruptions.