Subcutaneous injection of the seminal vesicle fluid of bulls into female mice which were subsequently mated resulted in a reduction in the number of embryos. The action of a number of different enzymes on the seminal vesicle fluid did not remove its antifertilizing activity.
The supernatant resulting from precipitation of the seminal vesicle fluid with acetic acid and ammonium sulphate had considerable antifertilizing activity. Injection of this fraction before and after mating demonstrated the antiembryonic character of the antifertilizing substance. Neither the number of ovulated eggs nor their fertilization was affected by the antiembryonic substance and there was no adverse effect on lactation, but the body weight of young, and even of adult, animals declined.
The antiembryonic substance affects the embryo at an early stage and continues to affect the organism for a long time. Necrotic changes can be observed in embryos as early as the 3rd day after the first injection. The number of leucocytes decreases for a short time after injection of the antiembryonic substance.
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