All About Placenta: Definition, Structure, Types and Uses

The placenta is a unique organ that forms during pregnancy in mammals, connecting the developing fetus to the maternal uterus. It plays a crucial role in supporting fetal growth, nutrient transfer, waste removal, and hormone production. Understanding the placenta is essential in fields like medicine, reproductive biology, and human development as it impacts both maternal and fetal health.

What is Placenta?

Placenta is a temporary but vital organ that develops in the uterus during pregnancy. Its main function is to act as a bridge between the mother and fetus, allowing the exchange of nutrients, gases, hormones, and waste products. In Hindi, placenta meaning is “गर्भनाल” (placenta meaning in Hindi). The placenta supports fetal development until birth when it is expelled from the body after labour.

Structure and Development of the Placenta

The placenta begins forming soon after implantation of the fertilized egg. It consists of both maternal and fetal tissues, making it a unique organ with combined origin. The fetal part, called the chorion, connects to the umbilical cord, while the maternal part lines the uterus wall. The placenta’s structure consists of villi, blood vessels, and membranes that facilitate efficient transport of materials.

Function of Placenta

The main function of placenta is to ensure the growing fetus receives nutrients, oxygen, and hormones required for healthy development. At the same time, it removes carbon dioxide and waste products. The placenta also produces several hormones, including progesterone and human chorionic gonadotropin (hCG), which are essential for maintaining pregnancy.

• Gas exchange: Transfers oxygen to the fetus and removes carbon dioxide.
• Nutrient absorption: Transports glucose, amino acids, and fats.
• Waste removal: Eliminates fetal wastes into maternal circulation.
• Hormone production: Supports maternal adaptations and fetal growth.
• Immune protection: Acts as a barrier to many infections.

Types and Positions of Placenta

Doctors categorize placentas based on their point of attachment to the uterine wall. These positions can influence pregnancy outcomes and are often identified via ultrasound.

• Anterior Placenta: Attached to the front wall of the uterus. “Placenta anterior” is commonly detected; some people wonder about placenta anterior means boy or girl, but position does not determine fetal gender.
• Posterior Placenta: Located on the back wall (placenta posterior). “Posterior placenta means boy or girl” is a common myth with no scientific basis.
• Fundal Placenta: Attached to the top wall of the uterus.
• Low Lying Placenta: Close to or covering the cervix, which may require monitoring (“low lying placenta”).

Placenta Previa

Placenta previa is a special type where the placenta partially or wholly covers the cervix. This condition can cause bleeding during pregnancy or delivery and may lead to a cesarean section.

• Complete previa: Entirely covers the cervix.
• Partial previa: Partially covers the cervix.
• Marginal previa: Edge touches, but does not cover, the cervix.

Other Variations

• Placenta accreta: The placenta attaches too deeply into the uterine wall, often leading to complications at birth.
• Circumvallate placenta: The placenta has a raised edge, which can affect its function.

Placental Development Process

The formation of the placenta involves several coordinated stages as the embryo implants and starts growing. This process ensures vital connections between mother and baby are established efficiently.

1. Implantation: The blastocyst embeds in the uterine wall.
2. Trophoblast formation: Cells differentiate to create the outer membrane (trophoblast), which invades maternal tissue.
3. Chorionic villi development: Finger-like projections form to increase surface area for exchange.
4. Blood vessel growth: Networks form, connecting the fetus and mother for nutrient and waste exchange.
5. Maturation: The placenta fully develops and functions until birth.

For more about fetal development, visit our page on embryo development and implantation in human.

Placental Disorders and Medical Relevance

Many medical conditions are associated with abnormal placental structure or position. These can affect both maternal and fetal health, sometimes requiring special care or intervention.

• Placenta previa: May cause heavy bleeding and require cesarean delivery.
• Placenta accreta: Placenta is abnormally adherent, risking hemorrhage during removal.
• Circumvallate placenta: Increases risks of preterm birth or fetal growth problems.
• Low lying placenta: Monitored via ultrasound for maternal safety.

Learn more about female reproductive system and structural adaptations on Vedantu.

Types of Placenta in Animals

Placental types differ across mammals based on their structure and attachment degree. In animals, these variations are important for evolutionary studies and veterinary medicine.

• Discoidal placenta: As in humans, forms a disc-like structure.
• Cotyledonary placenta: Found in cows and sheep with patch-like attachments.
• Diffuse placenta: Horses and pigs have villi spread over a large area.
• Zonary placenta: Present in dogs and cats, forming a belt around the fetus.

Visit our animal kingdom classification page to see how placental evolution fits into animal diversity.

Placenta After Birth

After childbirth, the placenta is expelled from the uterus in a stage known as “afterbirth.” Medical professionals examine the placenta to ensure its complete expulsion and to check for signs of disorders. In some traditions, the placenta holds cultural or symbolic meaning and may be treated in special ways post-delivery.

Placenta Diagram – Simplified Structure

A clear placenta diagram shows the chorionic villi, maternal and fetal blood vessels, and the umbilical cord. Visualizing these components helps biology students understand material exchange during pregnancy.

Explore other human anatomy diagrams on Vedantu, like our uterus diagram or parts of the brain for holistic learning.

Placenta Extract and Applications

Placenta extract gel is used in some medical and cosmetic products to promote healing or skin regeneration. While research continues, these applications highlight the biological significance of placental tissues beyond pregnancy, especially in the fields of medicine and health.

Page Summary

The placenta is a vital organ during pregnancy, enabling the exchange of essential substances between mother and fetus. By studying its types, functions, and disorders, students gain insights into reproductive biology and human health. Interested learners can explore related topics and diagrams on Vedantu for deeper understanding and academic success.