Quantification of Gestational Changes in the Uteroplacental Vascular Tree Reveals Vessel Specific Hemodynamic Roles During Pregnancy in Mice

ABSTRACT The purpose of this study was to establish the time course and hemodynamic significance of de novo formed and enlarged uteroplacental arteries during pregnancy. Using x-ray microcomputed tomography (n = 4–7 placentas from 2–4 dams/gestational group), uteroplacental arterial vascular dimensions were measured at individual implantation sites. Dimensions and topology were used to compute total and vessel-specific resistances and cross-sectional areas. Diameter enlargement of the uterine artery (+55% by Embryonic Day 5.5 [E5.5]) and preplacental radial arteries (+30% by E8.5) was significant only in early gestation. Formation of spiral arteries (E9.5–E11.5), maternal canals, and canal branches (E11.5–E13.5) during midgestation was followed by enlargement of these vessels such that, from E9.5 to E17.5 (near term), spiral artery resistance dropped 9-fold, and canal resistance became negligible. A 12-fold increase in terminal vessel cross-sectional area was nearly sufficient to offset known increases in...