The placenta is a temporary organ that connects the mother and fetus during pregnancy. It has two sides - the fetal side and maternal side - and consists of two membranes, the amnion and chorion, as well as the umbilical cord. The placenta performs vital functions like respiration, excretion, nutrition, and protection for the developing fetus.

1. THE PLACENTA
BY: G. LUNGU

5. Objectives
By the end of the presentation, learner should be able to describe:
• the placenta
• functions of the placenta
• Placenta at term
• Umblicol cord
• Membranes and amniotic fliud
• Abnormalities of the placenta

6. Description
• It is a temporary organ shared by the mother and fetus
• It develops from the outer layer of the pre-implantation embryo
• The pre-implantation embryo (blastocyst) is segregated into two
lineages: the inner cell mass and outer cell mass and outer cell mass
• The outer layer organises into trophoblasts, later becomes the
placenta

7. Description ct …
Trophoblast proliferates and separetes into:
• Inner cytotrophoblastic layer (fetal side)
• The synctiotrophoblastic layer – outer layer (placental side / maternal
side)

8. Fetal side Maternal side

9. FUNCTIONS OF THE PLACENTA
• RESPIRATORY FUNCTION – oxygen from the mother passes into the
placenta into fetal blood by diffussion.
• Similary, the fetus gives off carbon dioxide into maternal blood

10. Functions ct …
• EXCRETORY FUNCTION – end products of fetal metabolism such as
urea, bilirubin and carbon dioxide cross the placenta into maternal
circulation where they are excreted
• NUTRITION FUNCTION – mothers blood supplies the fetus with
nutrients such as CHO, water, salts, fats, proteins and minerals

11. Functions ct …
• PROTECTIVE FUNCTION – placental barrier protects the fetus from
many harmful substances. It is limited to viruses, bacilli, syphyllis,
hepatitis since these can cross the placental membrane

12. Functions ct…
• HORMONAL FUNCTION – oestrogen, progesterone, HCG and HPL are
produced by the placenta. They are responsible for preparing
maternal body for labour and lactation

13. Functions ct …
• PASSIVE IMMUNITY – immunity to diptheria, measles is passed to
fetus from maternal antibodies.

14. Placenta at term
• It is a connective link between
mother and fetus
• It is disc shaped organ, dark red
in colour on maternal side and
silver colour on the fetal side
• It is 20cm in diameter, 2.5cm
thick at the centre
• It weighs 1/6 of babys weight
(about 500g

15. Placenta at term ct …
• It has 2 surfaces i.e. Maternal and fetal side
• The chorionic membrane extends from its edges forming a chorionic
sac
• The chorionic sac is lined with amniotic membrane which is filled with
amniotic fluid
• All nourishment of the fetus is derived from the mother through the
placenta

16. Umblicol cord
• The connecting body or stalk
which joins the placenta and the
fetus
• It is usually inserted on lateral
sides of the placenta or into the
centre of the surface of the
placenta

17. Umblicol cord
• It is about 50 cm long and 1.5cm thick in diameter
UMBLICOL CORD INSERTION
• BATTLE DORE INSERTION OF THE CORD – The cord is inserted at the
very edge of the placenta

18. PLACENTA VELAMENTOSA – When the cord is inserted into the
membranes instead of the fetal surface of the placenta

19. BLOOD VESSELS OF THE UMBLICOL CORD
ONE UMBLICOL VEIN – It is a thin
walled wide lumen vessel which
carries 85% of oxygenated blood
from the placenta to the fetus
TWO UMBLICOL ARTERIES – Thick
walled and narrowed lumen. It
carries deoxygenated blood from
the fetus to the placenta.

20. • The blood vessels are
surrounded by a jelly like
substance known as whartons
jelly which protects and
supports them

21. Umblicol cord
• Sometimes the whartons jelly form lumps known as false knots.
• After delivery, inspect for presence of all the 3 vessels. A missing
artery / vessels is associated with a congenital abnormality

22. THE AMNION
• Also known as amniotic membrane
• The sac becomes filled with fluid derived from maternal circulation
• The fluid is called amniotic fluid or liquor

23. Amnion
• The sac increases in size until it
completely sorrounds the
embryo which freely floats in the
fluid
• It is tough, translucent and
smooth
• It ruptures at birth
• Some times the baby can be
born with it and can lead to
suffocation

24. THE CHORION
• It is a thick opaque membrane
• It is friable (easily breaks into small pieces)
• It Seen hanging from the edges of the placenta

25. NOTE: after delivery of the placenta and membranes, the 2 membranes
can be separated up to the point of cord insertion
• Amniotic membrane, chorionic membrane and fetal side of the
placenta forms the fetal sac.

26. Amniotic fluid
• It is similar to that of extra
cellular fluid
• 98% is water, 2% solids made up
of electrolytes, proteins,
creatinine, urea and uric acid,
glucose, fats and hormones
• It is clear alkaline fluid

27. ABNORMALITIES OF THE PLACENTA
• Placenta succenturiata
• Placenta bi partita or tripartita
• Placenta circumvallata
• Placenta infarct
• Placenta oedema
• Meconeum stained placenta and cord
• placenta acreta

28. Summary
• It is a temporary organ shared by the mother and fetus
• It is a connecting link between the mother and fetus
• It consists of two sides (fetal and maternal), two membranes (amnion
and chorion) and umblicol cord.
• It protects and supports the fetus by performing various functions
like: respiratory, excretory, nutritive and barrier

29. YEBO