Implantation and Placental Development Flashcards
how many days after fertilization does implantation in the uterine wall take place?
6-7 days
what are the three distinct phases of implantation by order?
apposition
adhesion
invasion
this phases is the initial contact of the blastocyst to the uterine wall
apposition
this phase is marked by the increased physical contact between the blastocyst and the decidua
adhesion
this phase is marked by the penetration and invasion of
syncytiotrophoblast and cytotrophoblast into the
decidua
invasion
these hormones are required to ensure success of implantation
estrogen and progesterone
Uterine receptivity is limited to days _____ of teh cycle
20-24
what is the dominant hormone during the luteal phase?
progesterone
adherence of the blastocyst is mediated by what?
cell mediated cell surface receptors that interact with blastocyst receptors
how many cells is blastocyst composed of during apposition
100-250 cells
apposition is also referred to as
initial unstable adhesion
what wall of the uterus does apposition occur?
posterior superior wall
what interaction does the blastocyst have with the decidua during implantation?
paracrine interactions
the embryonic microvilli interdigitates with the ____ of the decidua
pinopods
to further attachment of the blastocyst with the decidua, at day 6, these proteins and receptors interact with each other?
laminin and integrin
this protein stimulates migration
fibronectin
This implantation of the blastocyst is
the result of?
mutual trophoblastic and endometrial action.
trophoblasts differentiate into
syncytiotrophoblast and cytotrophoblast
this phase of implantation has a more stable connection is established
between the decidual wall and the embryo by the
modification of the expression of cellular adhesion
molecules (CAMs), especially of integrins.
adhesion phase
are cell-surface receptors that mediate
adhesion of cells to extracellular matrix proteins
Integrins
Give markers for receptivity expressed by integrins
αVβ3 and α4β1
phase where there is infiltration of mononuclear cytotrophoblast
invasion
what does the cytotrophoblast invade
entire endometrium
inner third of the myometrium
uterine vasculature
where does the human placental formation begin?
trophoectoderm
the invasiveness of the trophoblast promotes?
implantation
nutritional role for the conceptus
endocrine role
which of the differentiated trophoblasts is the inner layer, mononucleated
with a well-defined border
cytotrophoblast
which of the differentiated layer of the trophoblast is the outer
layer, polynucleated, has an amorphous
cytoplasm with no cell border
syncytiotrophoblast
the trophoblast is the inner or outer cell mass?
outer cell mass
what is the inner cell mass?
embryoblast
the differentiated embryoblast that becomes the germ layers
(endoderm, mesoderm, ectoderm) and the embryo
epiblast (columnar)
the differentiated embryoblast that becomes wall of yolk sac
hypoblast (cuboidal)
differentiated trophoblasts that generate chorionic villi,which
primarily transport oxygen, nutrients, and other
compounds between the fetus and mother
villous trophoblasts
differentiated trophoblasts that migrate into decidua
and myometrium and also penetrate maternal
vasculature, thus coming into contact with various
maternal cell types.
Extravillous trophoblasts
differentiated extravillous trophoblasts that nvade the decidua and
eventually penetrate the myometrium to form
placental-bed giant cells.
interstitial trophoblasts
differentiated extravillous trophoblasts that penetrates the lumen of the spiral artery
endovascular trophoblasts
on day 9 after fertilization, how many layers does the blastocyst have?
1 layer
when does the blastocyst become totally encased in the endometrium
10 days after fertilization
On what day after fertilization is the stage characterized by the
intercommunication of the lacunae filled with maternal
blood. This is also the day that : the hypoblast would have given rise to the
primitive yolk sac/extracoelomic cavity.
12 days after fertilization
cells from the yolk sac later forms the
extraembryonic mesoderm
this differentiated extraembryonic mesoderm becomes the (chorionic plate) - outer layer
becomes muscles, skin, skeleton etc
somatopleure
this differentiated extraembryonic mesoderm becomes the inner layer, becomes the viscera
(gut)
splanchnopleure
Cells of the syncytiotrophoblast penetrate deeper into the
stroma and erode the lining of the maternal capillaries
forming
sinusoids
The lacunae become continuous with the sinusoids
causing the maternal blood to enter the lacunar system
composed of trophoblasts and mesenchyme.
chorion
- joins the embryo to the nutrient chorion (that is
your placenta) and later develops into the umbilical cord.
stalk
day after fertilization where all teh cavities are formed: amniotic cavity, yolk sac, and chorionic cavity
day 13
hypoblasts cells gradually proliferate and migrate along
the inside of the exocoelomic membrane forming the
secondary or definitive yolk sac
when cytotrophoblasts penetrate the syncitiotrophoblasts, they form the
primary villi
primary villi is composed of syncytiotrophoblast covered in cytotrophoblast? t or f?
False
cytotrophoblast core covered in syncytiotrophoblast
these villi form approximately day 12 when
mesenchymal cords derived from extraembryonic
mesoderm invade the solid trophoblast columns. When primary chorionic villi acquire mesenchymal core
secondary villi
these villi are formed when e angiogenesis begins in the
mesenchymal cords.
The definitive placental villi.
Forms when there is Development of capillaries in secondary chorionic villi
tertiary villi
This is the day after fertilization when fetal blood vessels are functional and
placental circulation is established.
day 17
The villi are covered by an outer layer of syncytiotrophoblast
and inner layer of cytotrophoblast also called as
langhans cells
this villi extends from the chorionic plate to the decidua basalis
stem villi
branches of stem villi are called?
free villi
the base of the chorionic plate forms the
roof of the intervillous space
this is formed by 8-10 weeks
as the amnionic and primary chorionic plate mesenchyme
fuse together.
chorionic plate
Chorion in contact with decidua basalis with extensive
frond-like villous outgrowth into decidua
chorion fondosum
chorion fondosum plus the decidua basalis forms the
placenta
smooth chorion and this is an important site of molecular transfer and metabolic activity
Chorion leave
which part of implantation is integral to some pathological conditions such as pre eclampsia, fetal growth restriction and pre term birth?
invasion of the spinal artery
first wave of invasion of uteroplacental vessel development happens during when and up to what level
before 12 weeks post fertilization and up o the level of the border between the decidua and the myometrium
the second wave of invasion of uteroplacental vessels happens and and up to what level?
12-16 weeks post fertilization and up to the level of intramyometrial segments of the spiral arteries
remodeling of spiral arteries results in
dilated, low resistance uteroplacental vessels
in the first trimester, what grows faster? the fetus or plaenta?
placenta
● Approximately 17 weeks’ gestation, placental and fetal
weights are approximately equal.
● By term, placental weight is approximately one sixth of
fetal weight
what are the functional units of the placenta?
Lobes or cotyledons
around 10-38 cotyledons
what separates the cotyledons in the placenta?
placental septa
how heavy is the term placenta?
500-600 grams or 1/6 of the weight of the baby
which surface of the placenta is cobblestone in appearance? fetal or maternal?
Maternal
fetal surface is smooth due to amnion
amnion is nearer fetal surface
chorion is nearer maternal surface
what are the functions of the placenta?
nutrition excretion respiration protection hormone production
is the chorionic sac is fetal or maternal component of placenta?
fetal
decidua basalis is the maternal
fetal macrophages that infiltrate the stroma are called?
Hofbauer cells
the placental circulation has how many arteries and veins?
2 arteries and 1 vein
the blood in the intervillous space is maternal or fetal?
maternal
fetal blood lies in the chorionic villi
what carries the deoxygenated blood from the fetus to the mother?
umbilical artery
what carries oxygenated bloodfrom the mother to the fetus?
umbilical vein
the amnion is avascular? t or f?
True
the inner surface of the amnion is made up of?
single layer of cuboidal cells
the acellular compact layer of the amnion is composed primarily of
interstitial collagen
the outer layer of the amnion is composed of?
fibroblast like mesenchymal cells
the outer most layer of the amnion is composed of?
acellular zona spongiosa
what is the second fetal membrane?
Chorion laeve
when is the amnion first identifiable?
on the 7th or 8th day of embryo development
where does the epithelium of the amnion originate?
fetal ectoderm
amnion epithelial cells are metabolically active, what substances to these cells synthesize?
MMP1, PGE2 and fetal fibronectin (marker for pre term labor)
interstitial collagen is produced by what cells of the amnion?
mesenchymal cells
amnions tensile strength lies in the compact layer. What collagens are responsible for this strength?
Interstitial collagen I and II
by the 16th week how many mL of amniotic fluid is available?
200 mL
30 mL at 10 weeks
800 mL at mid third trimester
during the first half of pregnancy, there is transcutaneous flow on the skin of the fetus? t or f?
True
this serves as the protective layer of the blood vessels in the umbilical cord
Wharton’s Jelly
what is the major site of steroid and protein production in the placenta?
Syncytiotrophoblasts
cross stimulation of HCG is possible with this hormone?
TSH
as maternal serum hcg peaks, synthesis is almost solely in syncytiontrophoblast or cytotrophoblast?
syncytiotrophoblast
at 5 weeks, both syncytio and cyto
when does hcg enter the maternal blood?
at blastocyst implantation
hcg titer of what levels indicate intrauterine gestation?
1000-1500 IU/L
maximal level of of hcg is achieved at how many weeks which may be the reason for symptoms such as hyperemesis gravidarum?
8-10 weeks
lower plasma levels of hcg may be seen in
ectopic pregnancies
impeding spontaneous abortion
8 days after ovulation or 1 day after implantation, what rescues the corpus luteum?
hcg
what hormone is responsible for maternal lipolysis which increases free fatty acid levels in the maternal blood
HPL
which hormone has a diabetogenic action which causes insulin resistance and provides higher maternal glucose levels available for the fetus
HPL
hormone which is important in fetal lung maturation and timing of parturition
CRH
produced by the human corpus luteum responsible for myometrial smooth muscle relaxation
relaxin
what regulates trophoblastic production of hcg
GNRH
normally secreted by adipocytes which regulate fetal bone growth and immune function
leptin
what inhibits FSH release
Inhibin (inhibin A)
what stimulates FSH production and secretion
Activin
what is the precursor of progesterone?
Cholesterol
what is the precursor of estrogen?
DHEA
most important source of estrogen in pregnancy?
Fetal adrenal cortex
what causes the synthesized estrogen in the syncitium to go to the maternal blood
hemochorioendothelial form of placentation
