The Placenta

WHAT IS THE PLACENTA?

A temporary organ joining the mother to the embryo/fetus that enables the transfer of substances between the two, i.e. oxygen, nutrients, carbon dioxide.  It derives from the trophoblast cells.

FUNCTION OF THE PLACENTA...

The fetus depends on the placenta for its development and survival.  Its primary function is to enable the passing of substances between mother and fetus...

• MOTHER --> FETUS
  • Nutrients (e.g. glucose, amino acids, and minerals), water and oxygen pass from the mother's blood to the fetus's blood
• FETUS --> MOTHER
  • Carbon dioxide and urea pass from the fetus's blood to the mother's blood.

Antibodies also pass from the mother to the fetus.  This ensures that the fetus is protected from the same diseases as the mother.  This is a form of passive immunity and lasts for a short time after birth.

STRUCTURE OF THE PLACENTA...

The placenta contains a large number of chorionic villi containing foetal capillaries.  These ensure a maximum area of contact with the maternal blood.  The capillaries are separated from the maternal blood by a thin membrane.  This membrane has three layers:

• The wall of the villus consisting…