The potential relationship between uterine arterial and venous concentrations of progesterone, and porcine fetal size and viability was examined. Sixteen Yorkshire gilts were laparotomized at 27 to 37 days of gestation to count corpora lutea and embryos. Samples of blood were drawn from uterine arteries and veins at each embryonal location of 10 of the gilts but not from the six control gilts. At 60 to 76 days of gestation, a second laparotomy was performed to determine rates of fetal survival and to draw blood samples from uterine vessels at all fetal locations in each of the 12 gilts remaining from the first surgery. The percentages of embryos surviving between first and second surgeries were 51.0% for the experimental gilts and 65.6% for the control gilts (P>0.05). Progesterone concentrations were higher in arteries than in veins at each fetal location at both surgeries (P<0.01). The disappearance or utilization of progesterone in the uterine tissues surrounding either normal or mummified fetuses was greater late in pregnancy compared with the early embryonic stage (P<0.05). Uterine arterial and venous progesterone concentrations were unrelated to fetal weight; however, fetal weight was correlated with arterial-venous differences. These data suggest that some of the progesterone entering the uterine arterial system is metabolized or utilized and does not reenter the uterine venous system and that this utilization may be related to fetal weight and stage of development.
All Science Journal Classification (ASJC) codes
- Reproductive Medicine
- Cell Biology