Anatomy and Functions of Placenta

Gross Anatomy of the Placenta

It consists of two surfaces:

1. Fetal surface
2. Maternal surface

•   Maternal Surface

• Placenta is attached to the upper side of the fundus
• 15-20cm in diameter
• 30% of uterus covered by the placenta
• Center part is 2.5cm in thickness
• Thickness reduced at the periphery
• Convex polygonal areas called Cotilidons
• 16-20 cotilidons in a placenta
• Grayish areas are calcium deposits
• Greyish tinge is due to placental separation
• Each cotilidon has fissures which contain decidual septum

• Fetal Surface

• Fetal surface is grey and glistening
• Cord is the continuation of the mesoderm
• It is also called funis (50-100cm)
• It consists of two arteries and one vein
• At the cut end of the cord, vein appears collapsed and arteries are protruded and down.
• Cord is 50-100cm in length
• White jelly life substance called Wharton’s jelly present on the cord
• Inner layer is amnion and the outer layer is the chorion

Functions of the Placenta

1. The fetus obtains amino acids, glucose, vitamins, calcium, phosphorus, iron and other minerals from the maternal blood through the placenta.
2. The placenta also stores glucose in the form of glycogen. It also stores iron and fats soluble vitamins.
3. The waste products such as carbon dioxide, bilirubin and urea are excreted from the fetus through the placenta.
4. The placenta prevents passing of microorganisms from the mother to the fetus to some extent.
5. The placenta also produces hormones like the human chorionic gonadotrophic hormone, oestrogen, progesterone and human placental lactogen (HPL).