placenta and fetal membrane

Question 1

fetal component and maternal component of placenta is derived from

Answer 1

fetal- trophoblast and extraembryonic mesoderm (chorionic plate)
maternal- uterine endometrium

Question 2

changes in beginning of 2nd month

Answer 2

secondary and tertirary villi develop and give a radial appearance
( stem villi extend from extraembryonic mesoderm into the cytotrophoblast shell)

Question 3

surface of villi is formed by

Answer 3

synyctium which rest on a layer of cytotrophoblast and covers a core of vascular mesoderm

Question 4

extraembryonic vascular system

Answer 4

capillaries system developing in core of villus come in contact with the chorionic plate and the connecting stalk and makes the extraembryonic vascular system

Question 5

maternal blood to placenta is delivered by

Answer 5

spiral arteries

Question 6

endovascular invasion

Answer 6

erosion of maternal vessels to release blood into the intervillous system is done through endovascular invasion by cytotrophoblast

Question 7

how endovascular invasion is done?

Answer 7

cytotrophoblast released from the ends of villous replace endothelial cells of spiral arteries with hybrid vessels which contains both maternal and placental cells. cytotrophoblast undergo a epithelial to endothelial transition which transform the high resistance small diameter spiral arteries into low resistance more diameter vessels.

Question 8

chorion frondosum

Answer 8

early developmental days the villi surrounds the whole chorion but as pregnancy advances villi on embryonic pole enlarges and expand give rise to chorion frondosum (bushy chorion)

Question 9

chorion laeve

Answer 9

at the aembryonic pole villi degenerate and by third month this side of chorion is smooth known as chorion laeve

Question 10

decidua basalis

Answer 10

the decidua over the chorion frondosum is known as decidua basalis and has decidual cells. also called decidual plate which is tightly connected to the chorion and has lipids and glycogen

Question 11

decidua capsularis

Answer 11

the decidua over the aembryonic layer is decidua capsularis

Question 12

decidua parietalis

Answer 12

the chorion leave comes in contact with uterine wall (decidua parietalis) from opposite sides fuse together and obliterate the uterine lumen

Question 13

only portion of chorion participating in exchange are

Answer 13

chorion frondosum and decidua basalis makes up the placenta

Question 14

amniochorionic membrane

Answer 14

made by fusion of amnion and chorion makes the amniochorion membrane that obliterates the chorionic cavity and ruptures during birth

Question 15

placenta has 2 components in the beggining of what month

Answer 15

4 month
the fetal component made by chorionic plate
and the maternal component made by decidual plate

Question 16

junctional zone of placental and maternal areas

Answer 16

here the trophoblast and decidual cells intermingle

zone is characterized by giant decidual and syncytial cells with amorphous ecm

Question 17

decidual septa? formation in what month

Answer 17

4 to 5 months
there are many septas made by the decidua in the intervillous spaces but they are not in contact with the chorionic plate
they have a core of maternal tissue and are covered by syncytial cells so at all times the maternal blood is separated from the fetal tissues of the villi

Question 18

cotyledons

Answer 18

decidua septa divide the intervillous space into cotyledons

Question 19

4 layers of placental membrane

Answer 19

1. endometrium covering the fetal vessels
2. connective tissue making the core of villous
3. cytotrophoblast
4. syncytium

Question 20

how the rate of exchange of placenta is increased

Answer 20

the endothelial lining of vessels come in close contact with the syncytium which thins the placental membrane

Question 21

how much 02 does fetus extracts

Answer 21

20-30 ml of oxygen from maternal blood

Question 22

what is critical to oxygen supply to fetus

Answer 22

placental blood flow and depends on delivery not diffusion

Question 23

progesterone is produced by placenta at what month

Answer 23

at 4 month to maintain corpus luteum

Question 24

all hormones are produced by in placenta?

Answer 24

syncytial trophoblast

Question 25

hormones produced by placenta except progesterone

Answer 25

estrogen (estriol)

which maintain the uterine growth and development of mammary glands

Question 26

another hormone produced by placenta other than estrogen and progesterone

Answer 26

somatomammotropin hormone which priorities placenta for glucose on mother and that’s why the mother gets diabetogenic also promotes breast development

Question 27

what is present between amnion and and embryonic ectoderm

Answer 27

(amnio-ectoderm junction ) primitive umbilical ring

Question 28

what does the umbillical ring contains

Answer 28

1. connecting stalk- allantois and umbillical vessels
2. yolk stalk - (vitelline duct) contains vitelline vessels
3. canal connecting the intra and extra embryonic cavities

Question 29

yolk sac is present in

Answer 29

chorionic cavity between the amnion and chorionic plate

Question 30

primitive umbilical cord

Answer 30

the amniotic cavity enlarges at the expense of chorionic cavity and envelops the connecting and yolk sac stalk crowding them together to form primitive umbilical cord

Question 31

how yolk sac obliterates

Answer 31

yolk sac is present in chorionic cavity attached to the umbilical cord through its cord. when the amnion enlarges it attaches to the chorion obliterating chorionic cavity and the yolk sac degenerates