Comparative analysis of functions of cow and reindeer female reproductive organs: Progesterone content in vessels of reproductive organs

Progesterone content in blood from paired ovarian and uterine veins as well as from jugular veins of cows and reindeers was studied in the estrous cycle lutein phase and at the earlier stages of pregancy. In the both species, maximal progesterone concentration was detected in blood from vein of the ovary carrying corpus luteum (p < 0.001). In cows, a higher hormone concentration, as compared with jugular vein, has also been determined in vein of the uterus horn closest to ovary with corpus luteum (p < 0.01). In reindeers, blood from all studied vessels of reproductive organs had the progesterone concentration that was statistically significantly higher (p < 0.001) than that from jugular vein. In cows, progesterone concentration in blood from the ovarian vein was found to be higher when corpus luteum was located on the right ovary (p < 0.05) as compared with left-side corpus luteum location. No functional asymmetry of ovaries was revealed in reindeers. A possible role of mechanisms of the hormone local transport between ovary and uterus in adaptation of ruminants to reproduction under Nordic conditions is discussed.