University of wisconsin-madison


photo of mare ovary and oviduct

The oviduct (Fallopian tube, uterine tube) connects the ovary to the uterus horns and are 20-30 cm long. The oviduct is supported by the mesosalpinx and is very tortuous. Sperm travel up the oviduct prior to fertilization and the embryo travels down the oviduct after fertilization.

The utero-tubal junction is area where the uterine horn connects to the oviduct. The sperm arrive at the junction within 8 - 12 hours of insemination and then move up to the lower isthmus to colonize the oviductal sperm reservoir, that consist of the oviduct epithelial cells of the isthmus. The function of the sperm reservoir is to keep sperm viable until ovulation. At ovulation, sperm move up to the ampullar isthmic junction where fertilization occurs. On day 4 after ovulation, the embryo then moves to the uterotubal junction and into the uterus. If an oocyte is not fertilized, then it remains in the oviduct and does not enter the uterus.

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Mare Anatomy