Test: The Placenta and Fetal Membranes - NEET PG MCQ

The placenta was recognized and respected by ancient Egyptians for its role in supplying nutrition to the fetus, as understood by Diogenes of Apollonia around 480 BC.

The human placenta is hemochorial, where placental villi are directly surrounded by maternal blood, facilitating nutrient and gas exchange.

The average size of a placenta at term is approximately 22 cm in diameter, with a central thickness of about 2.5 cm and a weight of 450–500 g.

The syncytiotrophoblast, formed by the fusion of trophoblast cells, penetrates the uterine epithelium to facilitate embryo implantation during the prelacunar stage.

The intervillous space is formed from lacunae during the lacunar stage and is filled with maternal blood, surrounding the villous trees for nutrient exchange.

Maternal blood flow to the placenta begins at the end of the first trimester when trophoblastic plugs open, allowing maternal blood cells into the intervillous space.

Extravillous trophoblast cells invade maternal tissues, including the endometrial stroma and spiral arteries, to remodel blood vessels and ensure adequate oxygen and nutrient supply.

The chorion laeve is the fetal membrane formed by the regression of villi, resulting in a smooth surface, while the chorion frondosum develops into the definitive placenta.

Syncytial knots, formed through apoptotic processes, are extruded into the maternal circulation, carrying aged trophoblast material, primarily trapped in lung capillaries.

Doppler ultrasound, including pulsed and colour Doppler, assesses blood flow in the uterine and umbilical arteries, aiding in the detection of placental issues like intrauterine growth restriction (IUGR).