A three-dimensional study on human placental villi from normal and tubal ectopic pregnancy

Summary

The development of chorionic villus trees emerging from the chorionic plate in early intra-uterine and tubal pregnancy was studied by scanning electron microscopy. Early human placental samples between 4 and 10 weeks of pregnancy were obtained from legal abortions and hysterectomies.

The chorionic villus trees which emerge from the chorionic plate divide gradually into branches of which ramify as buds. These buds gradually grow and are transformed into shoots. The numbers of developing new villi appears to increase gradually from 28 days after conception to 12 weeks after the last menstrual period. From 4 weeks massive trophoblastic sprouts were observed on the surface of the main chorionic villi, which transform into primary, secondary and tertiary villus trees.

When placental villus formation in ectopic pregnancy was compared with intra-uterine pregnancy, no fundamental difference was observed. In ectopic pregnancy, the configurations of placental villi were compressed and also shrunken on three-dimensional analysis. The ramifications and new villus formation seen in normal placenta were decreased in magnitude and less frequent. Some placental villus samples displayed gradual thinning in the terminal region.