Figure 5.

Comparison of spiral artery remodeling in the nonpregnant, normal pregnant, and preeclamptic pregnant state: Normal, nonpregnant endometrium contains capillary beds and glands, which provide nourishment to the uterine endometrium. During pregnancy, these capillary beds and endometrial glands are destroyed, and the spiral arteries dilate and open directly into the intervillous space; thus, providing low-pressure, high-volume blood flow. In preeclampsia, some remodeling allows for a small degree of spiral artery dilation, but the volume of blood being delivered to the placenta is considerably less than in normal pregnancy.