Igura K, Zhang X, Takahashi K, et al. Isolation and characterization of mesenchymal progenitor cells from chorionic villi of human placenta. Cytotherapy 2004;6:543-53.
Gases and nutrients move back and forth between the decidua basalis and the fetal veins, by diffusing through the tissue layer of the thin chorionic villi.
By analyzing the villi that provide contact with the mother's blood to the fetal membrane, Muneta deduced that the fetus must be living in an environment of elevated ketones from the start of pregnancy.