Sperm distribution within the genital tract of naturally inseminated gilts

Twelve gifts were naturally inseminated by one of two fertile boars. The semen backflow collected during mating and during the subsequent two hours contained a mean number of 23 billion spermatozoa. The gilts were slaughtered at 2, 6 and 12 hours after mating. The numbers of spermatozoa were counted in the uterus, uterotubal junction and in four equally long segments of the oviduct. The numbers of spermatozoa recovered in the uterus diminished significantly during the first 12 hours after mating. The numbers of spermatozoa recovered in the UTJ did not vary significantly with the time factor. No relationship was found between ovarian activity and numbers of spermatozoa recovered from the ipsilateral uterine horn. The statistical comparison of the numbers of spermatozoa within oviductal segments in respect to time revealed no significant differences.