Myoendometrial versus placental uterine arteries: Structural, mechanical, and functional differences in late-pregnant rabbits


      OBJECTIVE: This study compared late-pregnant radial uterine arteries that supplied the placenta versus the myoendometrium to evaluate differences in active and passive mechanical properties.
      STUDY DESIGN: Pressurized segments of placental versus myoendometrial radial uterine arteries from late-pregnant (day 28 to 30) New Zealand White rabbits (n = 12) were compared in vitro for differences in luminal diameter, wall thickness, distensibility, and intrinsic tone as a function of transmural pressure.
      RESULTS: Both types of arteries responded to increased transmural pressure with active vasoconstriction; however, the amount of tone present in myoendometrial arteries was significantly greater than in placental arteries (percent tone at 75 mm Hg = 39% ± 3% for myoendometrial versus 31% ± 2% for placental arteries, p < 0.01). Measurements of unpressurized, fully relaxed arteries revealed that placental arteries were 38% larger in diameter and had thicker walls than myoendometrial arteries did. However, myoendometrial arteries were significantly more distensible at transmural pressures >5 mm Hg.
      CONCLUSIONS: The increased size and diminished tone of placental compared with adjacent myoendometrial arteries would favor increased blood flow to the placenta; differences in size and passive mechanical properties suggest that a localized factor(s) originating from the fetus or placenta contributes to the gestational enlargement of those arteries that perfuse the placenta. (Am J Obstet Gynecol 1997;177:215-21.)


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to American Journal of Obstetrics & Gynecology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Stock MK
        • Metcalfe J.
        Maternal physiology during gestation.
        in: The physiology of reproduction. Raven Press, New York1994: 947-958
        • Osol G
        • Cipolla M.
        Pregnancy-induced changes in the three-dimensional mechanical properties of pressurized rat uteroplacental (radial) arteries.
        Am J Obstet Gynecol. 1993; 168: 268-274
        • Moll W
        • Kunzel W.
        The blood pressure in arteries entering the placentae of guinea pigs, rats, rabbits and sheep.
        Pflugers Arch. 1973; 338: 125-131
        • Moll W
        • Kunzel W
        • Stolte LAM
        • Kleinhout J
        • deJong PA
        • Veth AFL
        The blood pressure in the decidual part of the uteroplacental arteries (spiral arteries) of the rhesus monkey.
        Pflugers Arch. 1974; 346: 291-297
        • Cipolla M
        • Osol G.
        Hypertrophic and hyperplastic effects of pregnancy on the uterine arterial wall.
        Am J Obstet Gynecol. 1994; 171: 805-811
        • Moll W
        • Espach A
        • Wrobel KH.
        Growth of mesometrial arteries in guinea pigs during pregnancy.
        Placenta. 1983; 4: 111-123
        • Moll W
        • Gotz R.
        Pressure-diameter curves of mesometrial arteries of guinea pigs demonstrate a non-muscular, oestrogen-inducible mechanism of lumen regulation.
        Pflugers Arch. 1985; 404: 332-336
        • Nienartowicz A
        • Link S
        • Moll W.
        Adaptation of the uterine arcade during pregnancy.
        J Dev Physiol. 1989; 12: 101-108
        • Takemori K
        • Okamura H
        • Kanzaki H
        • Koshida M
        • Konishi I.
        Scanning electron microscopy study on corrosion cast of rat uterine vasculature during the first half of pregnancy.
        J Anat. 1984; 138: 163-173
        • Ford SP
        • Reynolds LP
        • Magness RR.
        Blood flow to the uterine and ovarian vascular beds of gilts during the estrous cycle or early pregnancy.
        Biol Reprod. 1982; 27: 878-885
        • Nuwayhid B.
        Hemodynamic changes during pregnancy in the rabbit.
        Am J Obstet Gynecol. 1979; 135: 590-596
        • Duncan SLB
        • Lewis BV.
        Maternal placental and myometrial blood flow in the pregnant rabbit.
        J Physiol. 1969; 202: 471-481
        • Johnson RL
        • Gilbert M
        • Meschia G
        • Battaglia FC.
        Cardiac output distribution and uteroplacental blood flow in the pregnant rabbit: a comparative study.
        Am J Obstet Gynecol. 1985; 151: 682-686
        • Laird MR
        • Faber JJ
        • Binder ND.
        Maternal placental blood flow is reduced in proportion to reduction in uterine driving pressure.
        Pediatric Res. 1994; 36: 102-110
        • Boura ALA
        • Walters WAW
        • Read MA
        • Leitch IM.
        Autocoids and control of human placental blood flow.
        Clin Exp Pharmacol Physiol. 1994; 21: 737-748
        • Creasy RK
        • Resnik R.
        Fetal growth.
        in: Maternal-fetal medicine: principles and practice. WB Saunders, Philadelphia1989: 547-564
        • Osol G
        • Cipolla M.
        The interaction of myogenic and adrenergic mechanisms in isolated, pressurized radial arteries from late pregnant and nonpregnant rats.
        Am J Obstet Gynecol. 1993; 168: 697-705
        • Wiederhielm CA.
        Continuous recording of arteriolar dimensions with a television microscope.
        J Appl Physiol. 1963; 18: 1041-1042
        • Moll W
        • Kinzel W
        • Herberger J.
        Hemodynamic implications of hemochorial placentation.
        Eur J Obstet Gynecol Reprod Biol. 1975; 5: 67-74
        • Herberger J
        • Moll W.
        The flow resistance of the maternal placental vascular bed of anesthetized guinea pigs.
        Z Geburtshilfe Perinatol. 1976; 180: 61-66
        • Rosenfeld CR
        • Morriss Jr, FH
        • Battaglia FC
        • Makowski EL
        • Meschia G.
        Effect of estradiol-17β on blood flow to reproductive and nonreproductive tissues in pregnant ewes.
        Am J Obstet Gynecol. 1975; 124: 618-629
        • Ku DN
        • Cheng Z.
        The mechanical environment of the artery.
        in: Hemodynamic forces and vascular cell biology. RG Landes, Austin (TX)1993: 1-23
        • Guenther AE
        • Conley AM
        • VanOrden DE
        • Farley DB
        • Ford SP.
        Structural and mechanical changes of uterine arteries during pregnancy in the pig.
        J Anim Sci. 1979; 135: 247-251
        • Annibale DJ
        • Rosenfeld CR
        • Stull JT
        • Kamm KE.
        Protein content and myosin light chain phosphorylation in uterine arteries during pregnancy.
        Am J Physiol. 1990; 259: C484-C489
        • Bendz A
        • Lundgren O
        • Hamberger L.
        Countercurrent exchange of progesterone and antipyrine between human utero-ovarian vessels, and of antipyrine between the femoral vessels of the cat.
        Acta Physiol Scand. 1982; 114: 611-616
        • Knickerbocker JJ
        • Thatcher WW
        • Foster DB
        • Wolfenson D
        • Bartol FF
        • Caton D.
        Uterine prostaglandin and blood flow response to estradiol-17 beta in cyclic cattle.
        Prostaglandins. 1986; 31: 757-776
        • Langille BL
        • O'Donnell F.
        Reductions in arterial diameter produced by chronic decreases in blood flow are endothelium-dependent.
        Science. 1986; 231: 405-407
        • Banes AJ
        • Tsuzaki M
        • Yamamoto J
        • Fischer T
        • Brigman B
        • Brown T
        • et al.
        Mechanoreception at the cellular level: detection, interpretation, and diversity of responses to mechanical signals.
        Biochem Cell Biol. 1995; 73: 349-365
        • Resnik R
        • Killam AP
        • Barton MD
        • Battaglia FC
        • Makowski EL
        • Meschia G.
        The effect of various vasoactive compounds upon the uterine vascular bed.
        Am J Obstet Gynecol. 1976; 125: 201-206
        • Mellander S.
        Functional aspects of myogenic vascular control.
        J Hypertens. 1989; 7: S21-S30