Placenta & Immunology Flashcards
The infant is dependent on the placenta for what functions?
Pulmonary, Hepatic, Renal
Maternal blood spurts from the __________ into the placental intervillous space and bathes the outer syncytiotrophoblasts
uteroplacental vessels
True or False: Fetal and maternal blood are not mixed in this hemochorial placenta
True
Where does the human placental formation begin?
Trophectoderm aka Morula
What is the invasive fxn of the trophoblast?
promotes implantation
What is the endocrine fxn of the trophoblast?
Endocrine function: maternal physiological adaptations, pregnancy maintenance
8th day after fertilization, what cells are formed on the outside. These are multinucleated
Syncitiotrophoblast
8th day after fertilization, what cells are formed on the inside. These are Germinal cells for syncytium and there is a well-demarcated cell border, single nucleus, undergoes DNA synthesis and mitosis
Cytotrophoblast
After implantation, trophoblasts differentiate further along two main pathways. What are these 2?
Villous Trophoblast & Exravillous Trophoblast
What is the function of Villous trophoblast?
It gives rise to CHORIONIC VILLI, which primarily transports oxgen, nutrients and other compounds bet mother and baby
The extravillous trophoblast is further differentiated into what? (2)?
Interstitial Trophoblast & Endovascular Trophoblast
Fxn of Interstitial Trophoblast
invade decidua and penetrate myometrium to form PLACENTAL BED GIANT CELLS. They also surround spiral arteries
Fxn of Endovascual Trophoblast
penetrate spiral artery LUMEN. Converts it from narrow-lumen, muscular spiral arteries into DILATED, LOW-RESISTANCE UTEROPLACENTAL VESSELS
by the 10th day… Blastocyst becomes totally encased within the _________
Endometrium.
Embryo enlarges -> more maternal decidua basalis is invaded by syncytiotrophoblast
by the 12th day… syncitiotrophoblast is permeated by a system of intercommunicatiing channels called ______
Trophoblastic Lacunae
It is filled with Maternal Blood
What does the extravillous cytotrophoblast give rise to?
Solid Primary Villi = Cytotrophoblast (Langhan’s Cell) Core + Syncitiotrophoblast Cover
Trophoblast-lined labyrinthine channels form….
Intervillous space
the solid cellular columns form the…
Primary Villous Stalks
At 8-10 weeks, this is formed via fusion of amnionic and primary chorionic plate mesenchyme
chorionic plate formed
Once angiogenesis begins in the mesenchymal cores, what are formed?
Tertiary Villi
At what day does the maternal blood enter the intervillous space?
day 15
At the 17th day, fetal blood vessels are _____ & placental circulation is _________
Functional & established
What is the contact between the trophoblast & maternal blood
Hemochorial Placenta
Hemochorial Placenta can be subdivided into:
Hemodichorial and Hemomonochorial.
In early pregnancy,villi are distributed _______ of the chorionic membrane
over the entire PERIPHERY
What is the fetal component of the placenta?
Chorion Frondosum or Leafy Chorion
Which part of the chorion becomes the avascular fetal membrane that abuts the decidua parietalis?
Chorion Laeve or Smooth Chorion
This is composed of cytotrophoblasts and fetal mesodermal mesenchyme that survives in a relatively low-oxygen atmosphere
Smooth Chorion
During first half of pregnancy, these accumulate in the decidua and are found in direct contact w/ trophoblasts. They lack cytotoxic fxns and are able to dampen inflammatory TH17 cells
Decidual Natural Killer Cells
These cells play a regulatory role in inhibiting NK cell killing during pregnancy
Decidual Macrophages
These promote decidual invasion toward spiral arteries
IL-8 & interferon-inducible protein 10
When is the trophoblast highly invasive?
First trimester
Invasive trophoblasts secrete _______ that digest ECM and activate proteinases already present in the endometrium
Proteolytic enzymes
This appears to be critical for human trophoblst invasion
MMP-9
During this time, there is limited invasiveness of trophoblasts
Late Pregnancy
This promotes invasion into the endometrium
Insulin-like growth factor II
secreted by decidual cells which blocks the autocrine loop
Insulin-like factor binding protein type 4
Truncal/main stem villi = lobule/cotyledon
Functional Unit
The ff are functions of this type of cell found during placental maturation: Phagocytic Immunosuppressive Produces cytokines Regulates trophoblast function
Hofbauer cells
Which MHC/s are absent from villous trophoblasts?
I & II
Normal implantation depends on….
controlled trophoblastic invasion of maternal EM-decidua and spiral arteries
This regulate trophoblast invasion
Uterine Natural Killer Cells
Tough, pliable, tenacious membrane
Provides tensile strength of fetal membranes
Amnion
Amnion is first identified during…
7th or 8th day
the tensile strength of the amnion is due to….
Cross-linked interstitial collagens I (tensile strength) & III (+ tissue extensibility)
Until when does the amniotic fluid increase?
increases until 34 weeks, then declines
True or false:
As pregnancy advances:
Yolk sac becomesl larger
Pedicle grows shorter
Expanding amnion fuses with chorion laeve
Covers the placental disc and lateral surface of the body stalk UMBILICAL CORD/FUNIS
FALSE
As pregnancy advances:
Yolk sac becomesl SMALLER
Pedicle grows LONGER
Expanding amnion fuses with chorion laeve
Covers the placental disc and lateral surface of the body stalk UMBILICAL CORD/FUNIS
most common vascular anomaly in the absence of 1 artery
Meckel Diverticulum
2 routes of blood flow
Ductus venosus
Hepatic circulation
Umbilical arteries are obliterated and become….
Medial umbilical ligaments
This hormone is almost exclusively synthesized in the placenta. May be elevated in fetal kidney & malignant tumors
HCG
Peak of HCG
Complete molecule peaks at 8-10 weeks
Give the fxns of HCG
Rescue & maintenance of corpus luteum
Stimulation of fetal testicular testosterone secretion
Leydig cell replication: sexual differentiation
Stimulate maternal thyroid gland
Promotion of relaxin
Regulates expansion of uterine NK cells
low plasma HCG indicates…
Early pregnancy wastage (abortion), ectopic pregnancy
elevated plasma HCG indicates…
Multifetal pregnancy, erythroblastosis fetalis, GTD
Proportional to placental mass
Synthesis is stimulated by insulin and insulin-like growth factor-1
Inhibition is by PGE2 and PGF2a
Human Placental Lactogen
Actions of hPL
Promotes maternal lipolysis
Inhibits leptin secretion by term trophoblasts
Inc maternal β-cell proliferation
Potent angiogenic hormone
This persists after fetal demise
Placental Progesterone
principal precursor for placental estradiol synthesis
DHEA-S
most impt source of placental estrogen precursors
Fetal Adrenal Glands
source of 90% of placental estriol precursors
fetus
85-90% of progesterone and estrogen formed in
Syncitiotrophoblast
Fetal glands take up lipoproteins as a source of cholesterol.
(LDL>HDL>VLDL)
in Anencephaly there is high levels of
Fetal Adrenal Steroid Precursor
Used to assess level of serum estriol
maternal serum triple or quadruple screening test
what do you check in triple screen
alpha-fetoprotein (AFP),human chorionic gonadotropin(hCG), unconjugated estriol
what is added to the triple screen to be quad?
Inhibin A
