L6: placenta & fetal membranes Flashcards
What is the Functions of the fetal membrane?
Protection
What do the Fetal membranes include?
- Amnion
- Chorion > sheet membrane of extraembryonic origin to support the fetus
- Yolk sac
- Allantois > ( connective stalk - came from extraembryonic mesoderm)
From where do it develop? (the fetal membrane)
These develop from the zygote
What is the importance of the amnion and chorion?
- essential for fetal development
- Transfer of nutrients during 2nd and 3rd weeks of development
The amnion and chorion do not participate in…
the formation of the embryo or fetus > bc they are derived from the extraembryonic mesoderm
The yolk sac is incorporate as
primordium of the gut
When does Blood cells develop?
Blood cells develop in its wall from 3rd to 6th week of development
When does the Primordial germ cells appear in its wall?
in the 3rd week of development
What is the importance of the Allantois?
- forms urachus in the fetus
- and median umbilical ligament in the adult Blood cells develop in its wall from 3rd to 5th week
- Its blood vessels persist as the umbilical vein and arteries
What is the Functions of the placents?
Metabolism
Production of hormones
metabolism of placenta synthesizes what
Synthesis of glycogen, cholesterol, and fatty acids > provides nutrition
passive immunity from the mother to the fetus
Maternal immunoglobulin G
what are the hormones produced by placenta?
o Human chorionic gonadotrophin HCG
o Progesterone
o Estriol
o Somatomammotropin
abnormal secretion of Somatomammotropin leads to…..
pregnancy diabetes
When does the Placenta start to develop?
As soon as implantation > syncytiotrophoblast start invading the endometrium
What is the Placenta?
is a fetomaternal organ > fatal components and mother component
where does the fetal part develops from
from the chorionic sac
where does the maternal part derived from
the endometrium > blood source
hemochorial Type
no mixing in the blood (placenta)
Where does the Implantation of a blastocyst take place?
The endometrium of the uterus
what is the decidua?
- the functional layer of the endometrium in a pregnant woman
- which separates from the remainder of the uterus after childbirth > shut off after birth
How many regions of the decidua are there?
The three regions
decidua are named according to
their relation to the implantation site
what are the 3 regions of decidua?
- basalis
- capsularis
- parietalis
The decidua basalis
forms the maternal part of the placenta.
The decidua capsularis
overlies the conceptus.
decidua parietalis
is all the remaining parts of the decidua
what is the chorionic plate?
it is a layer of the extraembryonic mesoderm that marks the fetal part of the placenta
Amnion
sac that the baby will swim in
how many arteries & veins does the umbilical cord have
- 2 arteries > deoxygenated blood
* one vein > oxygenated blood
Describe the mother blood circulation?
- Arteries >oxygenated
* Vein > deoxygenated
why do we need to maintain villi
to allow blood to flow
between the spaces for gas exchange
What happens to the barrier from week 4 to the 4th month?
The barrier decreases end becomes thinner In order to ease the exchange
why does the villi changes their morphology?
to increase
the blood exchange due to the growth of the fetus
How many cotyledons Maternal side exhibit?
Maternal side exhibits 15-20 cotyledons separated by
decidual septa
what is decidual septa
These are spaces between the villi
What coveres the Fetal surface?
the chorionic plate, which is covered by the amnion.
What are the products that are carried away from the fetus by the umbilical arterys?
Waste products
o carbon dioxide, water, urea, uric acid ,Bilirubin
Other substances
o RBCs antigen
o hormones
What are the products that are brought to the fetus via the umbilical vein?
- Oxygen and nutrients
- Harmful substances
Non-transferable substances
cant pass
(ex: bacteria,heparin,transferrin IgS &IgM)`
The waste product will be disposed by
the umbilical circulation
Describe a Monozygotic twins ?
They come from one oocyte > but during the cleavage two embryoblast are formed
Monozygotic twins have
o One placenta
o One chorionic sac
o Two amniotic sacs
Describe a dizygotic twins?
Two different oocytes
dizygotic twins could be due to
- continuous AMH hormone secretion
- Or because both ovaries ovulated and released eggs at the same time
dizygotic twins have
- One placenta or two
- Two chorionic sac
- Two amniotic sacs
What are the presenter abnormalities ?
Placenta accreta:
Placenta percreta:
Placenta previa:
Placenta accreta:
is when the chronic villi goes deep goes into the myometrium
Placenta percreta:
is when the chromic villi goes through the myometrium and attaches to the perimetrium the only treatment is the removal of the uterus
Placenta previa:
is attaches of the embryo in the lower segment of the uterus > Interior OS of the uterus > needs cesarean section.
What are the Significance of amniotic fluid?
- Permits symmetrical growth of the embryo and fetus
- Acts as a barrier to infection
• Prevents adherence of amnion to
the embryo and fetus
- Permits normal fetal lung development
- Cushions the embryo and fetus
- Enables movement of the fetus aiding in muscular development
- Maintains homeostasis of fluid and electrolytes
Oligohydramnios?
Refers to when there is a shortage of aminiotic fluid, it can cause the baby to be born
with severe abnormalities including underdeveloped lungs and kidney agenesis
Polyhydramnios?
• Refers to when there is an excess of aminiotic fluid, it can cause the baby to be born
with severe abnormalities including anencephaly and esophageal atresia
