What is placental villous?
Chorionic villi are villi that sprout from the chorion to provide maximal contact area with maternal blood. After circulating through the capillaries of the villi, blood returns to the embryo through the umbilical vein. Thus, villi are part of the border between maternal and fetal blood during pregnancy.
What is placental circulation?
The fetal-placental circulation allows the umbilical arteries to carry deoxygenated and nutrient-depleted fetal blood from the fetus to the villous core fetal vessels. At term, maternal blood flow to the placenta is approximately 600–700 ml/minute.
What is the difference between chorionic villi and placental villi?
chorionic villi: These sprout from the chorion in order to give a maximum area of contact with the maternal blood. placenta: A vascular organ present only in the female during gestation. It supplies food and oxygen from the mother to the fetus, and passes back waste.
What are the different types of villi?
At the end of pregnancy, six types of villi can be found in the placenta: stem villi, tertiary mesenchymatous villi, immature intermediate villi, mature intermediate villi, terminal or free villi, and trophoblast buds.
How chorionic villi are formed?
Structure of a Mature Chorionic Villus The core of a villus consists of blood vessels and mesenchyme that is similar in composition to the mesenchyme of the umbilical cord. Scattered among the mesenchymal cells are large Hofbauer cells, which function as fetal macrophages.
Do villi have blood capillaries?
Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries ( amino acids and carbohydrates) and lacteals (lipids).
What causes abnormal growth of capillaries in placental tissue?
Chorangiosis is a vascular hyperplastic process of the terminal chorionic villi, resulting from longstanding low grade hypoxia in the placental tissue (Congenit Anom (Kyoto) 2009;49:71) Alterations of the terminal villus lead to an abnormal growth of fibrous and vascular tissues, with an increased number of capillaries in placental areas
What is the function of terminal villi in the placenta?
(4) Terminal villi are characterized by blood supplying capillaries and venous sinusoides, each vessel tightly connected to the surface, several developed as vasculosyncytial membranes. Function of terminal villi is to exchange fetomaternal gas and nutritions and to take part in hormone production and metabolic activity (Figs 1 A–C; 2 A–D) 1 .
Why is normal villous maturation important for the placenta?
Normal villous maturation is essential for optimized placental function adjusted to fetal demands of oxygen and nutrition. Ramification and maturation from predominating immature intermediate villi in the first and second trimester to the mature intermediate and terminal villi in the third trimester reflect dynamical adaptation processes.
Why does the capillary bed of the terminal villi vary?
The arrangement of the capillary bed in the terminal villi can vary from simple U-like loops to a richly branched network due to capillary elongation and sprouting. Some of the following data is from a histological study of human placental villi.
