Normal placenta contains fetal and maternal pa. Which is the MOST inner pa of placenta?
**Core Concept**
The placenta is a vital organ that develops in the uterus during pregnancy, facilitating the exchange of oxygen, nutrients, and waste products between the mother and the fetus. It is composed of both fetal and maternal tissues, with the fetal tissues contributing to the development of the chorionic villi and the maternal tissues forming the decidua basalis.
**Why the Correct Answer is Right**
The most inner part of the placenta is the chorionic villi, which are small, finger-like projections that increase the surface area for gas and nutrient exchange. The chorionic villi are lined with fetal capillaries and are surrounded by trophoblasts, which are the outer layer of cells that form the placenta. The trophoblasts differentiate into cytotrophoblasts and syncytiotrophoblasts, which play a crucial role in implantation and the development of the placenta.
**Why Each Wrong Option is Incorrect**
**Option A:** The decidua basalis is the maternal tissue that forms the base of the placenta, but it is not the most inner part of the placenta. It is the area where the trophoblasts invade the uterine lining, but it is not as deep as the chorionic villi.
**Option B:** The amnion is a membrane that surrounds the fetus and the placenta, but it is not a part of the placenta itself. It is a separate structure that helps to protect the fetus and maintain the amniotic fluid.
**Option C:** The chorion laeve is a part of the placenta, but it is not the most inner part. It is a thin membrane that covers the surface of the chorionic villi and helps to regulate the exchange of gases and nutrients.
**Clinical Pearl / High-Yield Fact**
The placenta is a dynamic organ that undergoes significant changes throughout pregnancy, and its development is closely tied to the health and well-being of both the mother and the fetus. Understanding the anatomy and physiology of the placenta is essential for obstetricians and midwives to provide proper care and management during pregnancy and childbirth.
**Correct Answer: C. Chorionic villi.**