Cannulation of the utero-ovarian vein in intact ewes: Hormone concentrations and blood gas levels during the oestrous cycle and early pregnancy

S. B. Hooper, D. W. Walker, G. D. Thorburn

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A technique for implanting and maintaining catheters in both utero-ovarian veins (UOV) of intact, conscious sheep has been developed. Both UOV catheters remained patent for more than 2 weeks in 72.7% of animals. In non-pregnant ewes, large pulses of PGF(2α) were observed in UOV plasma collected on days 13 to 16 of the cycle (frequency 1.3 ± 0.2/12 h; pulse height range 1.0-26.9 ng/ml). In contrast, on days 13 to 16 of gestation, significantly (P<0.001) fewer pulses of PGF(2α) (frequency 0.42 ± 0.2/12 h) were observed in both UOVs of pregnant ewes, which were significantly (P<0.001) smaller in amplitude (pulse height range 1.4-4.9 ng/ml). The maintenance of the corpus luteum (CL) during early pregnancy may therefore directly result from a decreased uterine PGF(2α) release. During the luteal phase (day 4-12), the PO2 of UOV blood draining an ovary containing a CL (UOV/CL) was significantly higher than blood in the contralateral UOV (P<0.001). By days 15 and 16 of the cycle, the PO2 of UOV/CL blood had decreased and was not significantly different to that observed in the contralateral UOV (P>0.1). On day 17, the PO2 of blood in both UOVs was elevated significantly compared to levels observed on the two preceding and the two following days (P<0.001). We consider that the higher PO2 in UOV/CL blood resulted from a very high luteal blood flow, and that the decrease on days 15 and 16 of the cycle resulted from a decline in luteal blood flow during luteolysis. The subsequent increase in PO2 of blood from both UOVs on day 17 was considered to result from an increased uterine blood flow.

Original languageEnglish
Pages (from-to)253-262
Number of pages10
JournalActa Endocrinologia
Issue number2
Publication statusPublished - 1 Jan 1986

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