Placenta

Front 1

What phase is the uterine endometrium in druing implantation? Days? What is the dominant hormone?

Back 1

Secretory phase, implantation window is days 19-21, dominant hormone is progesterone

Front 2

What stage is the embryo in during implantation

Back 2

Blastocyst with the trophoblast and ICM

Front 3

What embroynic structure mediates implantation

Back 3

trophoblast

Front 4

describe the differentiation of the trophoblast after it attaches to the endometrium

Back 4

The trophoblast cells proliferate by mitosis to form an acelluar mass of cytoplasm called the syncytiotrophoblast, the original layer remains cellular and is known as the cytotrophoblast

Front 5

Describe the development of the lacunae. Where? What do they form

Back 5

Lacuae appear within the syncytiotrophoblast. They coalesce to form a network of larger spaces. On day 12, secretions from the syncytiotrophoblast erode the endothelium of the endometrial spiral arteries allowing maternal blood to enter the lacunae, this established the uteroplacental circulation

Front 6

Describe the formatin of the chorionic plate and the further development of the uteroplacental circulation

Back 6

The trophoblast and associated EEM adjacent to the embryo forms the chorionic plate. Blood vessels form within the EEM of the plate and asastomose with those in the body stalk and those in the embryo. This allows nutrients from maternal blood within the lacunar network to diffuse into the vascular network within the chorionic plate and gain access to the embryo

Front 7

Where and when is hCG secreted

Back 7

secreted by the syncytiotrophoblast begining day 7, peaking week 8 and declining by the end of the first trimester. Stimulates testosterone production in embryo. Used for pregnancy test by end of week 2

Front 8

Describe the decidual reaction

Back 8

maternal reaction to implantation, stromal cells fill with lipid and glycogen, intraceullar spaces fill with fluid, spread through entire functional zone

Front 9

After the decidual reaction ,the uterine endometrium becomes known as the decidua. What are the three regions of the decidua

Back 9

names in relation to site of implantation
-basalis=tissue adjacent to site of implantatin
-capsullaris-encircles chorionic cavity
-Parietalis= remainder of uterine cavity

Front 10

How does implantation affect the myometrium

Back 10

high levels of progestrone decrase the contractility, estrogen stimulates mitotic activity of smooth muscles cells, helps uterus grow in size

Front 11

In which areas of the decidua do chorionic villi form

Back 11

basalis and capsularis

Front 12

Describe the formation of primary chorionic villi

Back 12

Cytotorphoblast cells within the deciduea basalis and capsularis proliferate and grow into the syncytiotrophoblast

Front 13

Describe the formation of secondary villi

Back 13

EEM forms a core withing th eprimary villi

Front 14

Describe the formation of tertiary villi

Back 14

A vascular plexus forms within the mesoderm core. Vessles in the tertiary villi anastomose with vessels forming in the chorionic plate which in turn anastomse with those in the body stalk

Front 15

Describe the structure of a tertiary (mature) chorionic villus

Back 15

Stem, intermediate, and terminal villi

Front 16

Describe the structure and function of a stem villi of a mature chorionic villi

Back 16

Part of the cytotrophoblast extends into the overlying syncytiotrophoblast and contacts the endometrium of the decidua basalis. The cells grow laterally and join with others to form a layer of cytotrophoblast adjacent to the decidua known as the cytotrophoblastic shell. The villis contain arteries and veins

Front 17

Describe the structure and function of an intermediate villus

Back 17

Branches of stem villi, float in intervillosu space, contain arterioles, venules, and capillary loops

Front 18

Describe the structure and function of terminal villi

Back 18

Most distal branches of villous tree. Contain dilated capillary loops call sinusoids

Front 19

Describe the junctional zoneof the placenta

Back 19

-interface for eventual detachment
-maternal side=functional zone of endometrium in the area of decidua basalis that is coated with cytotrophoblastic shell

Front 20

Describe the changes that occur to the chorion and decidua to form the chrion laeve and chorion frondosum

Back 20

-occurs during 2nd and 3rd month
-the villi in the decidua capsularis atrophy leaving the chorion laeve (smooth)
-the villi in the decidua basalis continue to growth and become the chrion fondosum
-the placenta is a union between the tissues of the chorion fondosium and the decidua basalis
-the chorion and amnion fuse creating a chorioamniotic membrane

Front 21

Describe the significance of endovascular invasion in the formation of placental circulation

Back 21

Cytotrophoblastic cells of teh shell erode the distal ends of the spiral arteries within the decidua basalis. The cytotorphoblast cells transform into endothelial cells replacing some of the maternal enodthelail cells. This creates a hybrid vessel that has an increased diameter and a lower resistance to flow.

Front 22

Chorionic tissue always separates fetal and maternal blood but the amount of tissue changes with time. Describe this change

Back 22

Inital placental barrier=syncytiotrophoblast +cytotrophoblast+ basement membrane+ EEM+basement mebrane + capillary endothelium
Placental Barrier @ 20 wks=thins by rarification of teh cytotorphoblast and thinning of syncytiotrophoblast, capillary endothelium often contacts the syncytiotrophoblast forming an epithelial palte

Front 23

How are
substances transported across the placental membrane

Back 23

incutes gasses, ions, water, glucose, drugs, steroid=diffusion
antibodies, disease agents, proteins= endocytosis/pinocytosis
metabolic waste and hormones out by exocytosis

Front 24

Describe the secretory activity of teh placenta

Back 24

Secretes hormones (hCG, lactogen, thyrotropin, corticotropin) estrogen, progeterone, placental proteins, prolactin, relaxin, glycogen ,cholesterol, FA. Note estrogen production is a cooperative effort between materna and fetal (adrenal cortex and placenta) sources

Front 25

How does the placenta protect the featus from the mother's immune sytem

Back 25

1. Surface of syncytiotrophoblast has no paternal MHC antigens

2. Maternal immune system is selectively supressed by IL-10, TGTb, PGF-2 and regulatory T cells

3. Decidual reaction sets up an immunologial privleged site for the embryo

Front 26

Describe the two sides of the placenta at birth

Back 26

fetal=shiny, covered with chorioanmiotic membrane, umbilical cord inserts here

Materal=muddy side, w/ placental cotyledons (hypertrophied tertiary chorionic villi)

Front 27

Describe placenta previa

Back 27

-premature tearing of the placental attachment
-usually caused by implantation too near the cervix, servity depends on exact attchment
-endometrium of cervix does not participate in decidual reaaction, implantation is not secure at this site
-risk factors= smoking, age, multiples, uerine anomalies or scaring

Front 28

Describe placenta accreta

Back 28

-implantation extends into the basal zone of the endometrium
-diffucult to remove placenta during delivery
-w/ Placenta increta, implantation extens all the way into the myometrium'
-Placenta percreta-implantation extens inot uterine serosa or another organ
-risk factors=multiple cesarean sections and placenta previa

Hint accreta ~ acreepa, the implantation creeps in

Front 29

Describe placental abruption

Back 29

placenta detaches from the uterus before birth. May be initiated by hemorrhage into the decidua baslis causing a split in the juctional layer. Decidual necrosis and placental infarcts result. Caude by mternal malnutrition, smoking , diabetes, hypertension ,trauma, drug abuse (cocaine)

Front 30

Describe a hydatidiform mole

Back 30

-embryo doesn't develop but trophoblast does
-incrased hCG into 2nd mo.
-Complete=only paternal DNA is present, may be caused by dispermy, can become malignant
Incomplete=amount of embryonic devleopment depends on ratio of DNA, usually does not become malignant

Front 31

Decribe velamentous cord insertion

Back 31

Umbilical cord attaches to the chorion and amnion rather than the placenta. Umbilical vessesl continue to the placenta between the membranes. Umbilical cessels may be easily torn causinig fetal exsanguination

Front 32

which parts of the endometrium participate in the decidual reaction

Back 32

all of the functional zone but not the basal zone

Front 33

what tissues make up the chorion

Back 33

trophoblast (syncytio and cyto) and extra-embryonic mesoderm

Front 34

between what layers do the stem villi extend

Back 34

the stem villis are rooted in the chorionic plate and extand toward the endometrium. A column of cytotorphlast extens from the tip of each stem villus. The extensions of cytotrophoblast from each villis join to form the cytotophoblastic shell tha tanchors the chorionic sac to the endometrium.

Front 35

Does maternal blood enter the fetus? Visa versa?

Back 35

Maternal blood does not enter the fetal circulation

A small amount of fetal blood enters the maternal circulation