Vascular corrosion casting of normal and pre-eclamptic placentas

Abstract

Pre-eclampsia is an important cause of maternal and fetal morbidity and mortality that is associated with decreased placental perfusion. In the present study, vascular corrosion casting was used to investigate the differences in structural changes of the fetoplacental vasculature between normal and pre-eclamptic placentas. An improved epoxy resin vascular casting technique was used in the present study. Casting media were infused into 40 normal and 40 pre-eclamptic placentas through umbilical arteries and veins in order to construct three dimensional fetoplacental vasculatures. The number of branches, diameter, morphology and peripheral artery-to-vein ratio were measured for each specimen. The results indicated that the venous system of normal placentas was divided into 5-7 grades of branches and the volume of the vascular bed was 155.5±45.3 ml. In severe pre-eclamptic placentas, the volume was 106.4±36.1 ml, which was significantly lower compared with normal placentas (P<0.01). The venous system of pre-eclamptic placentas was divided into 4-5 grades of branches, which was much more sparse compared with normal placentas. In additions, the diameters of grade 1-3 veins and grade 2-3 arteries were significantly smaller in severe pre-eclampsia (P<0.05). In conclusion, pre-eclamptic placentas displayed a decreased volume of vascular bed, smaller diameters of grade 1-3 veins and grade 2-3 arteries, and an increased peripheral artery-to-vein ratio, which may be a cause of the placental dysfunction during severe pre-eclampsia.

Keywords: placenta; pre-eclampsia; vascular casting; vascular reconstruction.

Figure 1.

Images of the two types of self-designed spiral metal pressurizing units used along with 20 or 50 ml disposable plastic syringes and puncture needles for injecting the casting media into placental vessels.

Figure 2.

Images of placental vasculature casts of normal pregnancy and pre-eclampsia. (A) The amniotic and (B) chorionic sides in two different representative normal pregnancy specimens are presented. (C) The amniotic and (D) chorionic side in a representative pre-eclamptic placental sample are also presented. (E) Velamentous cord insertion, with the lower part of the umbilical cord found outside of the placenta. (F) Placenta from a dizygotic twin pregnancy, with visible lower part of the umbilical cords and microvascular anastomosis between the two placentas. In each image, the placental venous system (with oxygen blood) is shown in red, while the two umbilical arteries (anoxemia), are shown in blue.