Figure 1.

(A) Image showing the main structural and functional elements of the exchange barrier of the normal placenta: IVS intervillous space with maternal blood; ST syncytiotrophoblast – the placental epithelium; Endo fetal capillary endothelium; FC fetal capillary with fetal blood. (B) Consequences of abnormal spiral artery invasion and conversion on the structure and function of the placenta. Hypoxia and ischaemia-reperfusion may lead to the formation of free radicals and/or inflammatory mediators such as damage-associated molecular patterns (DAMPS). These could cause: abnormal blood flow patterns in the IVS; decreased fetoplacental blood flow; altered structure of the exchange barrier (e.g. reduced surface area and increased thickness of the ST) with reduced nutrient transfer; increases and decreases in secretion of hormones, soluble receptors and other placental proteins and factors. All of these are potential targets for treatments of placental dysfunction.