AMNIOCHORIAL Meaning and
Definition
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Amniochorial refers to a type of placental attachment observed in some mammals, particularly in ungulates (hooved animals) such as horses, cows, and pigs. It describes the anatomical condition in which the embryonic sac, known as the amnion, adheres directly to the chorion, which is the outermost fetal membrane, allowing close contact between the fetal and maternal tissues.
This type of placentation is characterized by a highly intimate relationship between the mother's uterine lining and the outer fetal membrane. The chorioallantoic membrane, deriving from the fusion of the chorion and the allantois (a sac in the embryo that stores waste products), takes part in the exchange of gases and nutrients between the mother and the developing fetus.
Amniochorial placentation is distinct from other types, such as hemochorial (where fetal tissues come into direct contact with maternal blood) or endotheliochorial (where the fetal tissues are separated from the maternal blood by endothelial cells). In amniochorial placenta, the chorion is closely associated with the uterine lining, without disruption of the maternal blood vessels.
This type of fetal-maternal connection is regarded as primitive among mammals, as it is believed to appear early in evolutionary history. It is generally associated with animals that have a long gestation period and give birth to a relatively well-developed offspring. Amniochorial placentation is essential for supplying the developing fetus with oxygen and nutrients and facilitating the elimination of waste products, resulting in the nourishment and growth of the fetus until birth.
Etymology of AMNIOCHORIAL
The word "amniochorial" originated from the combination of two terms: "amnion" and "chorion".
- "Amnion": This term comes from the Greek word "amnion", which means "lamb's skin" or "membrane surrounding a fetus". It is derived from "amnos", meaning "lamb". The amnion is the innermost membrane surrounding the embryo of mammals, birds, and reptiles. It contains the amniotic fluid that protects and cushions the developing fetus.
- "Chorion": This term comes from the Greek word "chorion", which means "skin", "membrane", or "covering". It refers to the outermost membrane surrounding the amnion and the developing embryo. The chorion plays a crucial role in facilitating exchange between the embryo and its environment, as well as in the formation of the placenta.
Similar spelling word for AMNIOCHORIAL
- amniochorial, amniochorionic.
