Implantation And Formation Of Placenta 2 Flashcards by joseph dizon

Expands into to decidua
Outer pole faces the endometrial cavity
Inner pole forms the placenta

Blastocyst

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Aka leafy chorion

Forms when chorionic villi proliferates upon contact with decidua basalis

Chorionic frondosum

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As growth of embryonic and extra embryonic tissues continues

Blood supply to the chorion facing the endometrial cavity is restricted

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Aka smooth chorion

Portion of chorion that becomes the avascular fetal membrane that touches the decidua parietalis

Chorion laeve

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Chorion laeve composed of cytotrophoblast and fetal mesodermal mesenchyme that survives in

Low oxygen atmosphere

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Chorion laeve

Separated from the amnion by exocoelomic cavity

Near the end of 3rd month

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Important sites of molecular transfer and metabolic activity

Chorion laeve

Amnion

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More translucent than the amnion

Chorion laeve

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Paracrine arm of the fetal maternal communication system

Amniochorion

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Accumulate in decidua and are found in direct contact with trophoblast during first half of pregnancy

Decidua natural killer cells

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Decidua natural killer cells

Lacks of cytotoxic functions and are able to

Dampen inflammatory TH17 cells

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Inhibits NK cells killing during pregnancy

Decidual macrophages

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Decidua natural killer cells

It expresses both

IL8 and

Interferon inducible protein 10

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Decidua natural killer cells

Produce proangigenic factors that promotes vascular growth in the decidua

VEGF

Placental growth factor (PIGF)

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Secrete specific chemokines that attract the dNK cells to the maternal fetal interface

Trophoblasts

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They form cell columns that extend from the endometrium to the inner third of the myometrial

Extra villus trophoblast

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Requires invasion of endometrium and spinal arteries

Process occurs under low oxygen conditions

Hemochorial placental development

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Secrete proteolytic enzymes that digest extracellular matrix and activate proteinase already present in the endometrium

Invasive trophoblast

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Invasive trophoblast produce urokinase type plasminogen activator which converts plasminogen into

Plasmin

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Degrades matrix proteins and activates matrix metalloproteases

Plasmin

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Appears to be critical for human trophoblast invasion

MMP-9

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Ability to invade maternal tissue in early pregnancy compared with limited Invasiveness in late pregnancy is controlled by?

Autocrine factors
Paracrine trophoblastic factors
Endometrial factors

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Secrete insulin like growth factor 2 acts in an Autocrine manner

Trophoblast

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Secrete insulin like growth factor binding protein type 4 that block Autocrine loops

Decidual cells

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Degree of trophoblast invasion is controlled by

Matrix degradation regulation | Factors that cause trophoblast migration

Low estradiol levels in the first trimester are critical

For trophoblast invasion and | Remodeling of spinal arteries

Occurs in the first half of pregnancy | Important to utero placental blood flow

Invasion of spiral arteries

Invasion of spinal arteries Integral to pathological conditions such as

Pre eclampsia Fetal growth restriction Preterm birth

Invasion of spinal arteries Carried out by two populations of extravillous trophoblast

Interstitial trophoblasts | Endo vascular trophoblast

Aggregate around the spiral arteries | Vessel preparation for endo vascular trophoblast invasion

Interstitial trophoblast

Enter to the spiral arteries lumens | Initially from cellular plugs

Endo vascular trophoblast

Endo vascular trophoblast Destroy vascular endothelium via

Apoptosis

Invasion by trophoblast involves only the decidual spiral arteries

Not decidual veins

2 stages of utero placental vessel development

First wave - before 12 weeks, post fertilization | Second wave - between 12-16 weeks

Maternal blood enters the

Intervillous space

Blood is propelled outside of the maternal vessels and sweep over and directly bathes the

Syncytiotrophoblast

Placental growth and maturation Placental growth is more rapid than fetus

First trimester

Placental growth and maturation Placenta and fetal weights are equal

17 weeks AOG

Placental growth and maturation Placenta weight is 1/6 of fetal weight

By term

Placental growth and maturation Slightly elevated convex areas from the maternal surface

Lobes

Placental growth and maturation Grossly visible lobes

Cotyledons

Placental maturation Abundant loose intercellular matrix in early pregnancy

Villous stroma

Placental maturation Fetal macrophages Nearly round with vesicular, often eccenteric nuclei and very granular or vacuolated cytoplasm

Hofbauer cells

Fetal circulation Deoxygenated blood flows to the placenta through the

Two umbilical arteries

Fetal circulation Umbilical vessels branch repeatedly beneath the

Amnion and villi

Fetal circulation Oxygenated blood returns from the placenta bia

Umbilical vein

Fetal circulation Umbilical vessels that traverse along the fetal surface of the placenta in the chorionic plate. Responsive to vasoactive substances

Placental surface | Chorionic vessels

Fetal circulation 65% of placentas, chorionic arteries form a fine network supplying the

Cotyledons

Fetal circulation Perforating branches of the surface arteries that pass through chorionic plate.

Truncal arteries

Each truncal arteries supplies

One main stem villus | One cotyledon

Maternal circulation Maternal blood enters through the ________ and is driven high up toward the ________ by arterial pressure.

Basal plate | Chorionic plate

Maternal circulation After bathing the external micro villus surface of chrorionic villi, maternal blood drains back through__________ in the _______ and enter _________.

Venous orifice Basal plate Uterine veins

Maternal circulation Maternal blood transverse the placenta randomly without

Performed channels

Maternal circulation Trophoblast invasion of the spiral arteries creates low resistance vessels that accomodate massive increase in

Uterine perfusion during gestation.

Maternal circulation Uterine wall Spiral arteries are

Perpendicular to it

Maternal circulation Uterine wall Veins are

Parallel to it

Maternal circulation Arterial openings into the Intervillous space becomes gradually reduced by

Cytotrophoblast invasion

Maternal circulation Uterine wall How many spiral arteries entries into the Intervillous space at term

120

Maternal circulation Uterine wall A prominent venous plexus separates the deciduas basalis from the myometrial and thus participates in providing a cleavage plane for placental separation

After the 30th week

Maternal circulation Uterine wall Increased during contraction

Placental lenght Thickness Surface area

Maternal circulation Larger volume of blood is available for exchange even though the rate of flow is decreased.

During contractions

Maternal circulation Principal factors regulating Intervillous space blood flow

Arterial blood pressure Intrauterine pressure Uterine contraction pattern Factors acting on arterial walls

Immunological consideration of the Fetal Maternal Interface With their inefficient cytotoxic abilities

Decidual natural killer cells

Immunological consideration of the Fetal Maternal Interface Populate the deciduas

Invasive trophoblast

Immunological consideration of the Fetal Maternal Interface Only fetal derived cells in direct contact with maternal tissues

Trophoblast

Immunological consideration of the Fetal Maternal Interface Act to control the invasion of trophoblast, which have adapted to survive in an immunologically hostile environment

Maternal NK cells

Human analogue of the major histo compatibility complex

Human leukocyte antigen

MHC clas 1 and 2 antigens are absent

Villus trophoblasts

Express MHC class 1 molecules

Invasive extravillous cytotrophoblast

Trophoblast HLA class 1 expression Encodes the major class I class Ia

ABC

Trophoblast HLA class 1 expression Encodes major class Ib

EFG

Trophoblast HLA class 1 expression Combined with unique expression of three specific HLA class I genes in extravillous cytotrophoblast

Uterine decidual natural killer cells

Trophoblast HLA class 1 expression Expressed only in humans Expression is restricted to extravillous cytotrophoblast adjacent to maternal tissues

HLa-G antigen

Trophoblast HLA class 1 expression A solute major isoform which has increased levels during pregnancy

HLA G2

Distinctive lymphocytes originate in bone marrow and belong to the natural killer cell

Uterine Natural Killer Cells

Uterine Natural Killer Cells Infiltration is increased by

Progesterone Stromal cell production of IL15 Decidual prolactin

Uterine Natural Killer Cells Secrete large amounts of _________ means that they are in an activated state

Granulocyte macrophage colony stimulating factor

Distributed over the entire periphery of the chorionic membrane

Villi