The Functional Unit: Chorionic Villi

A cross-section schematic showing maternal blood (red) in the intervillous space surrounding villi containing fetal blood vessels (blue/red).

First- and second-year medical students, OB/GYN rotations, reproductive biology courses, and nursing programs.

Advanced embryology fellows or researchers expecting transcriptomic/3D ultrastructural data.

To move from maternal to fetal blood, substances must cross the placental barrier , which consists of four main layers:

A side-by-side comparison diagram of a thick 1st-trimester villus vs. a thin 3rd-trimester villus.

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