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Concentrations of progesterone in uterine and arterial tissue and in uterine and jugular venous plasma were determined. Blood was collected on Days 4 and 9 postestrus from the jugular vein and the first and last venous branches draining each uterine cornu; uterine tissue and arteries were subsequently collected. Progesterone was greater (p less than 0.05) in the cranial third than in the middle or caudal thirds of the uterine horn adjacent to the corpus luteum (CL)-bearing ovary or in any third of the contralateral horn. Progesterone in uterine arterial segments adjacent to the CL-bearing ovary was higher (p less than 0.05) than in contralateral segments. Progesterone was higher (p less than 0.05) in blood from the first venous branch of the cranial third of the uterine cornu adjacent to the ovary with the CL, than in the last branch of the caudal third, or contralateral horn, or in jugular blood. When oviductal veins were resected on Day 9 postestrus, progesterone in the first vein draining the cranial third of the uterine cornu adjacent to the CL-containing ovary was not different (p greater than 0.05) 48 h after resection than in the same vessel in the opposite horn or in jugular blood. We concluded that progesterone and other ovarian products may be delivered to the uterus locally.

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Multiparous dairy cows were sampled to study the concentrations of progesterone in tissue of the uterus and associated vasculature and to determine whether progesterone was delivered to the uterus locally. In study 1, progesterone was greater (p<0.05) in the first venous branch draining the cranial portion of the uterine cornu adjacent to the ovary with a corpus luteum than in jugular blood or in the same vein draining the opposite uterine cornu on day 11 postestrus.Concentrations of progesterone were also greater (p<0.05) in the cranial than in the caudal half of the uterine cornu adjacent to the luteal-bearing ovary or in the cranial and caudal halves of the opposite uterine cornu. Concentrations of progesterone were also greater (p<0.05) in the uterine or ovarian arterial tissue adjacent to the ovary with the corpus luteum than in those same vessels on the contralateral side. In a second study, progesterone at 0 h on day 11 postestrus was greater (p 0.05) in the first venous branch draining the cranial portion of the uterine horn adjacent to the luteal-bearing ovary than in jugular blood, the same vein in the contralateral uterine cornu or in the same uterine vein 48 h after ligation and resection of the oviductal vein adjacent to the ovary with the corpus luteum. It is concluded that progresterone is delivered locally to the uterus and associated vasculature and the route of local delivery appears to be via the oviductal vein.