Placenta

Question 1

3 major functions of placenta

Answer 1

organ of exchange, produces hormones (progesterone, hCG, somatomammotropin), immunological barrier

Question 2

Hemochorial

Answer 2

maternal blood comes in direct contact with the chorion

Question 3

Fetal component of placenta

Answer 3

villous chorion (chorionic villi)

Question 4

Maternal component of placenta

Answer 4

decidua basalis (deep to conceptus)

Question 5

Umbilical cord structure

Answer 5

2 umbilical arteries, 1 umbilical vein, Wharton’s jelly (mucous connective tissue)

Question 6

decidua capsularis

Answer 6

decidua lying directly over the conceptus

Question 7

decidua perietalis

Answer 7

decidua not below or above conceptus

Question 8

Cotyledons

Answer 8

small compartments on maternal side of placenta

Question 9

Components of villous chorion

Answer 9

Trophoblast and extra embryonic mesoderm

Question 10

Functions of cytotrophoblast shell

Answer 10

• Firmly attaches the chorion to the endometrium
• Perforated by maternal vessels to supply and drain blood from intervillous spaces
• Degenerates by term and is replaced by fibrinoid material

Question 11

Stem (anchoring) villi

Answer 11

extend from the chorionic plate to the decidua basalis

Question 12

Terminal villi

Answer 12

branch from the side of anchoring villi and represent sites where the nutrient and gas exchange will occur between maternal and fetal blood

Question 13

Initially (by month 4), the outer surface of the terminal villi form a placental membrane that consists of 4 layers:

Answer 13

Syncytiotrophoblast
Cytotrophoblast
Extraembryonic mesoderm
Fetal endothelium

Question 14

By the beginning of month 4, the cytotrophoblast degenerates, leaving only 2 layers in the placental membrane:

Answer 14

Syncytiotrophoblast

Fetal endothelium

Question 15

Chorionic frondosum

Answer 15

Villi proliferate on the embryonic pole

Question 16

Chorionic laeve

Answer 16

Chorionic villi degenerate on ab-embryonic pole

Question 17

Amniotic fluid is comprised of…

Answer 17

Initially, amniotic fluid is secreted by cells of the amnion and some is derived from maternal blood, tissue and interstitial fluid by diffusion. Beginning in the 11th week, the fetus contributes to the amniotic fluid by excreting urine into the amniotic cavity

Question 18

Amno chorionic membrane

Answer 18

Membrane between the amnion and the chorionic laeve

Question 19

Functions of amniotic fluid

Answer 19

Allows for fetal movements
Prevents adherence between amnion and embryo
Shock absorber
Barrier to infection
Promotes lung development

Question 20

Amniocentesis

Answer 20

Sampling of amniotic fluid to test for genetic abnormalities

Question 21

Amniotic bands/constriction ring syndrome

Answer 21

Tears in the amnion may result in amniotic bands that encircle the fetal limbs or digits resulting in deformations

Question 22

Polyhydramnios

Answer 22

Excess of amniotic fluid. Correlated with maternal diabetes and disorders of central nervous system and gastrointestinal tract (various atresias) that prevent the fetus from swallowing amniotic fluid.

Question 23

Oligohydramnios

Answer 23

too little amniotic fluid; may result from failure of the fetal kidneys to form or amniotic fluid leakage. Severe oligohydramnios early in pregnancy is a risk factor for lung hypoplasia (lung underdevelopment)