intervillous

Intervillous is an anatomical term referring to the intervillous space of the placenta, the cavity between the fetal chorionic villi. This space is filled with maternal blood and surrounds the vessels and capillaries within the villi.

During placental development, chorionic villi extend into the intervillous space. Maternal blood is delivered to the space by uterine spiral arteries, creating a continuous flow that surrounds the villi and supports exchange with the fetal circulation.

The barrier between maternal and fetal blood is formed mainly by the syncytiotrophoblast lining of the villi, with cytotrophoblast, connective tissue, and fetal capillary endothelium contributing to the structure. Exchange of oxygen, nutrients, and waste occurs across this interface, allowing the fetus to obtain sustenance while remaining distinct from maternal blood.

Clinically, abnormalities of the intervillous space—such as reduced flow or intervillous thrombi—can indicate placental insufficiency or maternal vascular malperfusion and are associated with pregnancy complications including preeclampsia and fetal growth restriction. Placental pathology may note intervillous thrombus or related findings as part of broader assessments of placental health.

This term is used descriptively in obstetric anatomy and placental pathology to distinguish maternal-space aspects from intravillous components and fetal blood flow pathways.