<prompt> Regarding orientation of spiral arteries, which of the following is trueBoth arteries and veins are perpendicular to the uterine wallBoth arteries and veins are parallel to the uterine wallArteries are perpendicular and veins are parallel to the uterine wallVeins are perpendicular and arteries are parallel to the uterine wall  <response>: Spiral arteries are perpendicular and veins are parallel to uterine wall. This aids in closure of veins during a uterine contraction and prevents exit of maternal blood from intervillous space. 