[09.10] The Placenta V2

Fetal, Maternal

What are the two components of the placenta?

Decidua basalis, Chorion frondosum

What are the maternal and fetal components of the placenta?

Hatching

What process occurs when the blastocyst is removed from the zona pellucida?

End of the 1st, 2nd

When does implantation start and end?

Syncytiotrophoblast

Which part of the blastocyst eats its way into the endometrium?

Placenta previa

What placental abnormality occurs when the placenta is implanted, covering the endocervical canal?

Painless vaginal bleeding on the 3rd trimester of pregnancy

What is a sign of placenta previa?

Abdominally

If the placenta covers the internal os, how must the baby be delivered?

Placenta accreta

What placental abnormality occurs when the placenta attaches to the myometrial layer?

Hysterectomy

What procedure must be done if a large portion of the placenta is left and a manual extraction is unsuccessful to remove the placenta?

Abruptio placenta

What placental abnormality may occur secondary to hypertension where the placenta separates while the baby is in utero?

Uterus tetanically contracts which is very painful

What is a sign of abruptio placenta?

Human chorionic gonadotropin (hCG)

What hormone does the syncytiotrophoblast release?

Corpus luteum

hCG acts on what part of the female anatomy to sustain the production of progesterone?

Multiple pregnancies

hCG levels double in women with what condition?

Hyperemesis gravidarum

Increased hCG levels contribute to what condition?

Progesterone

What hormone is needed to maintain the secretory endometrium of pregnancy?

Estrogen

Administration of large doses of what hormone is found in morning after pills?

Inhibits the formation of the secretory endometrium and Interferes with the transport of the oocyte to the uterine cavity for implantation

What is the action of a morning after pill?

Prevents sperm from joining the egg and Prevents embryo from planting in the uterus

What is the action of an IUD?

Decidua

What are the changes that happen to the uterine mucosa once pregnancy occurs?

Glycogen and lipids

Endometrial cells accumulating what substances characterize decidual reaction?

Provides and immunologically privileged site for the conceptus, Protects maternal tissue from uncontrolled invasion of syncytiotrophoblast during implantation, and Source of nutrients for the growing embryo

List the functions of decidual cells.

Decidua basalis, Decidua capsularis, Decidua parietalis

What are the three regions of the decidua based on its relation to the implantation site?

Connecting stalk

What embryonic structure suspends the embryo in the chorionic cavity and develops into the umbilical cord?

Outer lining: Syncytiotrophoblast, Middle lining: Cytotrophoblast, Inner lining: Extraembryonic Mesoderm

List the components of the chorionic membrane.

Cytotrophoblast

What cells proliferate all over the chorionic sac via several mitotic divisions, pushing its way into the syncytiotrophoblast?

Primary chorionic villi

The proliferation of cytotrophoblast pushing its way into the syncytiotrophoblast form what structures?

Extraembryonic mesoderm

What pushes its way to the primary chorionic villi, forming secondary chorionic villi?

Mesodermal core (inner), Cytotrophoblast (middle), Syncytiotrophoblast (outer)

List the layers of the secondary chorionic villi under a microscope from inner to outer.

Blood vessels

With further development of the placenta, what structures will now start to develop within the mesodermal core?

Tertiary chorionic villi

Once blood vessels are found within the mesodermal core, this is called what?

Stem and free villi

Besides primary, secondary, and tertiary villi, how else can villi be classified?

Stem villi

What type of villi extend from the chorionic plate to the decidua basalis?

Free villi

What type of villi are the site of exchange of nutrients?

Cytotrophoblastic shell

What layer proliferates so fast that it extends out of the syncytiotrophoblast, forming a continuous layer surrounding the entire chorionic sac?

Ensures that the embryo is firmly attached to the endometrium

What is the function of the cytotrophoblastic shell?

Connecting stalk

What embryonic stalk suspends the embryo in the chorionic sac and later develops into the umbilical cord?

Vitelline stalk

What is the connection between the secondary yolk sac in the primitive gut?

Chorion laeve

What is the smooth chorion called that no longer has villi?

Chorion frondosum

What structure forms the placenta and is the fetal component which contains the chorionic villi that has extensively branched and grouped in its respective area

Decidua basalis and Chorion frondosum

What are the two components of the placenta in terms of maternal and fetal origin?

Chorion laeve

The chorion associated with decidua capsularis will gradually degenerate and become what structure?

Decidua parietalis and decidua capsularis

As the baby grows, the uterine cavity will gradually be obliterated, causing what two decidual layers to fuse?

Amniotic membrane

What membrane encloses the amniotic cavity?

Amniochorionic membrane

As the amniotic cavity enlarges, it obliterates the chorionic cavity and causes the amnion and chorion to fuse, leading to the formation of what membrane?

Bag of waters

What is the ruptured amniochorionic membrane called?

Amniotic Cavity & Chorion Frondosum and Decidua Basalis

What are the fetal and maternal parts of the placenta, respectively?

Syncytiotrophoblast (outermost), Cytotrophoblast, Connective tissue of villus, and Endothelial cell of fetal capillaries

List the components of the placental membrane.

Lacunae

Spaces appear in the syncytiotrophoblast, forming what structures?

Stem villi and terminal villi

The development of chorionic villi form what structures?

Maternal and Fetal

Blood in the lacunae (intervillous spaces) is from what source and blood vessels in the villi are from what source, respectively?

Free or terminal villi

Where does the exchange of nutrients take place in the placenta?

Endometrial arteries

What maternal vessels erode and allows blood to enter lacunae forming primordial uteroplacental circulation?

Placental septa

What is the part of the decidua not eroded by the villi called?

Cotyledons

The formation of placental septa divides the fetal part of the placenta into what structures?

Two or more stem villi and many terminal villi

What does each cotyledon consist of?

Discoid

What shape is the placenta?

Cobblestone

What appearance does the maternal side of the placenta have?

Attachment of umbilical cord

What structure is found on the fetal side of the placenta?

Amnion

What membrane covers the fetal side of the placenta, making it smooth and shiny?

Chorionic cavity

What is the space between the amnion and chorion called?

Amniochorionic membrane

What membrane is depicted as a dark wavy line on the fetal side of the placenta?

Chorionic plate

What acellular structure lies below the amniochorionic membrane?

Hypertrophic and basophilic decidual cells

The maternal side of the placenta is identified through what type of cells?

Endometrial arteries

What arteries push blood through gaps in the cytotrophoblastic shell?

Intervillous spaces

Blood from the endometrial arteries goes into what spaces where exchange of nutrients take place?

Endometrial veins

After bathing the free villi, blood drains back towards the mother through what vessels?

Umbilical arteries

What fetal vessels drain waste materials and carbon dioxide from the baby?

Endometrial veins

Waste products diffuse out into the intervillous space before being drained into what maternal vessels?

Syncytiotrophoblast (outermost layer), Cytotrophoblast (inner layer), Mesodermal Core (Connective tissue of villus), Endothelium of fetal capillaries (Blood vessels)

List the layers of the placental membrane that nutrients must penetrate to enter the villi.

Cytotrophoblast: made up of cuboidal cells, Syncytiotrophoblast: no discernable cell boundaries, multiple nuclei

What is the difference between cytotrophoblast and syncytiotrophoblast?

Umbilical Vein and Umbilical Artery

What vessels carry oxygen-rich blood from placenta to fetus and carry oxygen-poor blood and embryo waste products from fetus to placenta, respectively?

Thin out

As the placenta ages, what should happen to the placental membrane to increase exchange of nutrients?

Decrease in number of cytotrophoblasts, Formation of syncytial knots, and Deposition of fibrin in the placenta

List changes that occur as the placenta ages.

Syncytial Knots

What are the clumped up nuclei of syncytiotrophoblasts called?

600 mL

Around what volume is the fluid content of amniotic fluid?

Thermoregulation, Lubrication, Liquid shock absorber, and Monitoring of progression of pregnancy and predict fetal outcomes

List the functions of amniotic fluid.

Polyhydramnios and Oligohydramnios

What clinical correlations are associated with too much and too little amniotic fluid, respectively?

Two arteries and One vein

How many arteries and veins are in the umbilical cord?

Wharton’s jelly

What is the mesenchyme that surrounds umbilical vessels?

Umbilical arteries and Umbilical veins

What vessels carry DEOXYGENATED blood from fetus to placenta/mother and carry OXYGENATED blood from placenta/mother to fetus, respectively?

Hatching

What is the process where the blastocyst will now gradually emerge out of the zona pellucida like an egg hatching?

Placenta previa, Placenta accreta, and Abruptio placenta

List some abnormalities in placentation.

Inhibition through the administration of large doses of estrogen and the use of intrauterine device (IUD)

How can implantation be inhibited?