Placental Development

Question 1

Day 9-10 (placenta)

Answer 1

▪️lacunae form in syncytiotrophoblast

-maternal blood fills lacunae

Question 2

Day 11-13 (placenta)

Answer 2

▪️primary chorionic villi

-cytotrophoblast grow into lacunae

Question 3

Day 15-16 (placenta)

Answer 3

▪️secondary chorionic villi

• primary chorionic villi begins to branch
• EEM invades

Question 4

Day 21 (placenta)

Answer 4

▪️tertiary villi

-mesoderm cells differentiate into connective tissue and blood vessels that connect with embryonic blood vessels

Question 5

End of 4 week (placenta)

Answer 5

▪️complex vascular network develops allowing maternal-embryonic exchanges
▪️arteries carry deoxygenated blood whilst veins carry oxygenated blood

Question 6

Placenta functions

Answer 6

▪️exchange of gases- O2, CO2, CO
▪️exchange of nutrients and electrolytes
▪️transfer maternal antibodies IgG~14weeks
▪️hormone production-progesterone, hCG, somatomammotropin (GH)

Question 7

Placental abnormalities

Answer 7

▪️placenta previa
-overlies internal os of the uterus coving birth canal
▪️placenta accreta
-abnormal adherence