Placenta

Question 1

Implantation and placenta formation occur with invasion of the endometrium during what phase?

Answer 1

secretory phase

Question 2

What does the fertilized egg form prior to implantation?

Answer 2

early blastocyst with an inner cell mass and a trophoblast

Question 3

What day does implantation typically occur?

Answer 3

day 6 post fertilization

Question 4

What region of the blastocyst makes contact with the endometrium?

Answer 4

the embryonic pole

Question 5

What does the trophoblast do in the region attached to the endometrium?

Answer 5

the cells int hat area become cytotrophoblasts and they will give rise to the syncytiotrophoblast, which is an invasion into the endometrial lining

Question 6

Which are mitotically active - the cytotrophoblasts or the syncytiotrophoblasts?

Answer 6

cytotrophoblasts

Question 7

Describe te syncytiotrophoblast

Answer 7

it’s really a syncytia - there are no cell boundaries - it’s just a mass that invades into the epithelium

Question 8

Eventually, the developing fetus will bore further into the endmetrial stroma. WHat happens to the endometrial capillaries and blands?

Answer 8

THey get destroyed and end up as lacuna in the syncytiotrophoblast

Question 9

WHat do these lacunae do eventually?

Answer 9

fuse to form a lacunar network (eventually the intervillous spaces)

Question 10

At what point (day) has the embryo completely bored its way into the stroma?

Answer 10

day 9-11

Question 11

What will the lacunae contain?

Answer 11

maternal blood and endometrial gland secretions

Question 12

What will the cytotrphoblast build out to grow?

Answer 12

they will make pillars out into the interface between the syncytiotrophoblast, and the endometrium stroma. THese are the primary villi!

eventually they will get there and will form an outer shell aroundthe syncytioblast

Question 13

What do the chorioni villi eventually consist of? THree types of cells….

Answer 13

extraembryonic mesoderm
cytotorphoblast
syncytiotrophoblast

Question 14

Primary villin have only what?

Answer 14

syncytiotrophoblast on the outside and cytotorphoblast on the inside - no extraembronic mesoderm yet

Question 15

At what point do the villi have mesoderm ingrowth into the core?

Answer 15

secondary villi

Question 16

What happens for the villi to become tertiary?

Answer 16

the mesoderm core will become vascularized

Question 17

Anchoring villi are what?

Answer 17

a subtype of tertiary villi with a cytotorphoblastic shell

this occurs via invasion of cyto through the syncytio so that the cytotorphoblast cells will make direct contact with the decidual cells

Question 18

What do the cytotorphoblasts form after they penetrate through the syncytriotrophoblast?

Answer 18

the cytotrophoblastic shell

Question 19

What is the difference between an anchoring villus and a free villus?

Answer 19

the anchoring villus will be anchored to the cytotorphoblastic shell while the free villus are free

Question 20

Describe the decidual reaction?

Answer 20

transformation of endometrial stromal cells shortly after the embryo burrows in

the cells swell due to glycogen and lipid accumulation

the transformation spreads throughout superficial layers of the endometrium

Question 21

What do we call the oart of the placenta that has the most decidual change - where it burrows?

Answer 21

the decidual basalis - between the conceptus and myometrium - constitues the maternal portion fo the placenta

Question 22

What is the decidua capsularis?

Answer 22

the decidua between the conceptus and uterine lumen

it becomes attenuated and smooth - it’s continuous with the decidual basalis and the part of the decidual associated with the rest of the wall

Question 23

What is the name for the decidua associated with the remainder of the uterine wall?

Answer 23

decidual parietalis

Question 24

What are cotyledons?

Answer 24

partitioning of the decidual basalis - about 15-30 lobules divided by septae

within each lobule you expect to see 2-4 tertiary villi and their branches

Question 25

Describe fetal placental circulation in general?

Answer 25

umbilical arteries - chorionic arteries - villar capillaries - chorionic veins

Question 26

What supplies the placenta from the mom?

Answer 26

the spiral arteries of the uterus —-into the intervillous spaces —–drained by the endometrial veins

Question 27

After the first trimester, what happens to the placental barrier/

Answer 27

the cytotorphoblast and the mesoderm diminish significantly, leaving just the syncytiotrophoblast and basal lamina and then fetal capillaries

becomes very attenuated

Question 28

What infections can pass through the placental barrier?

Answer 28

TORCH
Toxoplasmosis
Other (hep B, Coxsackie, syphilis, VZV, HIV, PB19)
Rubella
CMV
HSV

Question 29

What is the main placental hormone in the beginning of pregnancy

Answer 29

HCG

Question 30

What does that hCG do?

Answer 30

maintains corpu sluteum and its production of progesterone and estrogen

Question 31

What are the two steroidal hormones produced by the synctiotrophoblast cells?

Answer 31

progesterone after the 1st trimester

estrogen

Question 32

THe placenta cannot make the precursor for estrogen, so where does it get it?

Answer 32

the androgens form the fetal adrenal cortex!

Question 33

Human placental lactogen is also called what?

Answer 33

chorionic somatomammotropin

Question 34

What is HPL associated with?

Answer 34

growth, lactation and lipid/carb metabolism

Question 35

What hormones are produced by the decidual cells?

Answer 35

prolactin, prostaglandins, and relaxin