"maternal component: decidua basalis is the inner portion of the placenta, which is formed by trophoblastic invasion of endometrium"
"fetal component: chorion frondosum is formed by an arterial plexus (branches of the umbilical artery), protruding into intervillous spaces as chorionic villi"
"Placenta is derived from the Greek word, plakuos, meaning "flat cake" 1 and this reflects its typical appearance. The placenta was noted by Aristotle and Galen, but the term originates with Fallopius who called it the "placenta uterina"."
Expected headings
"Embryology"
"Practical points"
"The placenta at term weighs ~470 g and measures ~22 cm in diameter with a thickness of 2.0-2.5 cm 3. Placental thickness is usually directly proportional to gestational age, to the extent that it can often predict the gestation weeks (e.g. 21 mm thickness at 21 weeks gestation)."