Placenta and Fetal membranes S2M3

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The placenta is a fetomaternal organ, what regions are fetal, and which maternally derived
- Fetal - Chorion Frondosum (Villus chorion)
- Maternal - Decidua basalis
What are the three layers of the Decidua
- Decidua basalis
- Decidua capsularis
- Decidua parietalis
Decidua basalis
- Portion of the endometrium that forms the maternal part of the placenta
- Connects embryo to the uterus
Decidua capsularis

Superficial part of the decidua that overlies the conceptus (embryo) distal to the stalk
Decidua parietalis

This is the portion of the decidua that lines the uterine wall accept where the stalk connects
Chorionic villi cover the entire chorionic sac until when

Beggining of the 8th week
Smooth chorion

Villi in the decidua capsularis become compressed and degenerate forming an avascular bare area called the smooth chorion
What happens to the chorionic villi in the decidua basalis area

They increase in number and size forming the chorion frundosum
Chorionic cavity

This is the space between the amniotic cavity and the decidua where the eventual chorionic villi emerge
Fetomaternal junction

This is where the Villi chorion is attached to the decidua basalis by the cytotrophoblastic shell where Endometrial arteries and veins pass through
Amniochorionic membrane

This is the fusion of the amniotic sac and the smooth chorion which adheres to the decidua parietalis
What membrane ruptures during labor

Amniochorionic membrane
Placenta Septa

Wedged shape areas of decidua that project to the chorionic plate creating incomplete compartments
What is the intervillus space lined by

Syncytiotrophoblasts
How does the maternal blood not mix with the fetal blood

Maternal blood flows into the intervillus space from the spiral arteries and flows over the branched villi transfereing nutrients but not blood
What is transfered to the fetus in maternal/fetal circulation
- Nutrients
- Electrolytes
- Glucose
- Amino Acids
- Free fatty acids
- Carbohydrates
- Vitamins
What is not transfered to the fetus
- Cholesterol
- Triglycerides
- Phospholypids
What takes oxygenated blood to the fetus from the placenta

Umbilical vein
Blood returns to the mother from the placenta through

Endometrial veins
What are the layers of the placental membrane
- Syncytiotrophoblasts
- Cytotrophoblasts
- Connective tissue
- Endothelium of the fetal capillaries
When does the placental membrane reduce to 2 layers instead of 4

20th week when the cytotrophoblasts decrease in number
What two membranes remain after the placental membrane reduces to two layers
- Syncytiotrophoblasts
- Endothelium of fetal capillaries
What are the general functions of the Placenta
- Metabolism
- Transport gases and nutrients
- Endocrine secretion
By what methods does transportation happen across the placenta
- Simple diffusion
- Facilitated diffusion
- Active transport
- Pinocytosis
What is the only antibody that crosses the placenta
- IgG
- "Gestation"
What are some of the diseases that a fetus can gain immunities to
- Diphtheria
- Smallpox
- Measles
Erythroblastosis fetalis

Rh+ blood in the mother stimulates attack of Rh- blood of the fetus, killing the fetus
Syncytiotrophoblasts of the placenta produce what proteins and steroid hormones
- Human chorionic Gonadotropin (hCG)
- Human chorionic Somatomammotropin (hCS)
- Human chorionic Thyrotropin (hCT)
- Human chorionic Corticotropin (hCACTH)
What is the role of hCG

Maintains corpus luteum and is used to determine pregnancy in mothers urine in the 2nd week
What is the role of hCS
- This allows the fetus priority on the maternal blood glucose (this can cause the mother to be diabetogenic)
- It also promotes breast development and milk production
When does the placenta take over as the main provider of progesterone

By the fourth month
When does Estriol reach its max in pregnancy, and what is its role
- Just before the end of pregnancy
- It stimulates uterine growth and development of mammary glands
What are the only proteins that cross the placenta
- T4
- T3
- Unconjugated steroids
- Diethystilbestrol (synthetic estrogen)
What are some viruses that cross the placenta
- Rubella
- Cytomegalovirus
- Coxsackie
- Variola
- Varicella
- Measles
- Poliomyelitis
Toxoplasmosis gondii causes what defects

Damage to the brain and eyes
The amnionic cavity enlarges rapidly during development and eventually

Envelops the connecting stalk and yolk sac stalk resulting in the primitive umbilical cord
What is the role of the amnionic fluid
- Absorbs jolts
- Allows fetal movement
- Prevents adherence to the amnion
- Maintains body temp
- Barrier to infections

Author

lancesadams

95287

Card Set

Placenta and Fetal membranes S2M3

Description

Micro Anatomy

Updated

2011-08-15T14:39:43Z

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