Placenta And Fetal Membranes Flashcards

1
Q

What is included in the fetal membranes?

____ separates the fetus from the endometrium.

The interchange of substances (nutrients and O2) occurs between the ____ and _____ _____ via the placenta.

Vessels in the ____ connect the placental circulation with the fetal circulation.

A

Chorion, amnion, umbilical vesicle, and allantois

Placenta

Maternal and fetal bloodstreams

Umbilical cord

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2
Q

The zygote is a ____ structure that can give rise to any structure in the body.

The expression of cell linage specific transcription factors begin in the ___. The ____ becomes the embryo and the ____ becomes the extra-embryonic tissue.

What are the two types of trophoblast layers?

A

Totipotent

Blastocyst; embryoblast; trophoblast

Polar trophoblast layer: direct contact with the embryoblast

Mural trophoblast layer: surrounding blastocyst cavity

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3
Q

When does implantation occur?

The polar vs the mural trophoblast layer designate an ____ pole vs _____ pole and directs how implantation will proceed.

The ____ is directed towards the endometrium. And the ____ is directed towards the uterine cavity.

The embryoblast becomes the ______ and has two layers called the _____ and ____.

____ forms the germ layers.

___ forms the extraembryonic structures including what?

A

2 week

Embryonic; non-embryonic

Embryoblast; blastocyst cavity

Bilaminar embryonic disc; epiblast; hypoblast

Epiblast

Hypoblast: amniotic cavity, amnion, umbilical vesicle, connection stalk, chorionic sac

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4
Q

When is blastocyst implantation completed?

The ____ contacts the endometrium and diffentiates in two what two cell type? What are their fx?

A

2nd week

Trophoblast

Cytotrophoblast: inner layer(organized)

Syncytiotrophoblast: outer layer; invades and displaces the decidual cells of the endometrium; produce hCG which enters the maternal blood via lacunae network

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5
Q

What is an ectopic pregnancy?

Where does this occur?

Does it produce hCG?

What are the signs?

A

Implantation of blastocyst outside of uterine cavity

Ampulla and isthmus of oviduct

Yes, but at a slower rate than normal pregnancies (+ pregnancy test)

Abdominal pain, amenorrhea, vaginal bleeding, rupture of the oviduct wall

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6
Q

What is the amnion?

What is the fx of the amnioblasts?

Describe primordial uteroplacental circulation?

A

Thin, though membrane that surrounds the embryo/fetus and amniotic fluid; continuous with epiblast cells

Separate from the epiblast -> enclose the developing amniotic cavity

O2 and nutritive substances pass to the embryo via diffusion through lacunae networks

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7
Q

____ will eventually obliterate the chorionic cavity and forms the epithelial covering of the ____.

The umbilical cord came from the _____.

A

Amnion; umbilical cord

Connecting stalk

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8
Q

What is the fx of the amniotic fluid?

What is it derived from?

Water content changes every ___ hours and exchanges with fetal ____ via the umbilical cord.

Fluid is secreted from what? Excreted?

What are the normal volumes at 10, 20, and 37 weeks?

A

Cushions the fetus inside the uterus, provides space for fetal movements and regulates fetal body temp

Maternal tissue and interstitial fluid

3; blood

Respiratory system and GI tract; fetal urinalysis system

30mL, 350mL, 700-1000mL

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9
Q

What is hydramnios?

What are the clinical signs?

A

Excessive amniotic fluid

Genetic defect, fetal defect in CNS, or blockage of the GI tube

Abdominal pain, swelling, bloating, breathlessness

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10
Q

What is oligohydramnios?

What does this cause?

A

Insufficient amniotic fluid

Problem with fetal development (renal agenesis, pulmonary hypoplasia)

Placental abnormality

Decreased fluid does not provide enough cushion to the fetus and umbilical cord (club foot)

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11
Q

After implantation, the endometrial wall closes off around the conceptus called a ____.

Then, the ____ surrounds the amnion and primary umbilical vesicle (yolk sac).

____ separates and splits mesoderm into two layers forming cavities that will make up the _____.

Where is this from?

As the extraembryonic mesoderm splits and the cavities combine, they form the ____ , which is a fluid-filled cavity that surrounds amnion and umbilical vesicle.

A

Closing plug

Extraembryonic mesoderm

Extraembryonic mesoderm; chorion

Hypoblast

Extraembryonic coelom

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12
Q

____ lines the trophoblast and covers the amnion and ____ surrounds the umbilical vesicle. They form a space called the extraembryonic coelom.

What is the primary vesicle that pinches off?

Amnion and umbilical vesicle are attached to the chorion via the ____.

What is the chorionic sac?

A

Extraembryonic somatic mesoderm; extraembryonic splanchnic mesoderm

Secondary umbilical vesicle (yolk sac)

Connecting stalk

Extraembryonic somatic mesoderm, cytotrophoblasts, and syncytiotrophoblasts

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13
Q

When does the chorionic villi appear?

What do the chorionic processes form?

What do they grow into and what are they induced by?

Projections form ____, first stage of placental development

Cover entire chorionic sac until when?

A

End of 2nd week

Vascular, syncytial columns

Syncytiotrophoblasts; extraembryonic somatic mesoderm

Primary chorionic villi

8th week

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14
Q

What does the chorionic villus originate from and what is it derived?

What separates fetal vessels from the maternal blood in the intervillous space?

What makes up the placental barrier?

Each villus has a core of what?

A

Chorionic plate; derives from stem villus giving rise to villous branches

Placental barrier

Cytotrophoblast and syncytiotrophoblasts cells and supporting basal lamina/basement membranes; endothelial cells and basal lamina of the fetal blood capillaries

Mesenchymal CT and fetal blood vessels

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15
Q

What is the functional layer of the endometrium that separates from the remainder of the uterus after parturition?

What are the three parts?

What is the decidual reaction?

A

Decidua

Decidua basalis: deep to the conceptus, forms maternal part of the placental (where the placenta anchors into the maternal tissue)

Decidua capsularis: superficial and overlies conceptus (encapsulates the fetus)

Decidua parietalis: remaining parts of the decidua; lined with functional layer

Cellular and vascular changes occurring as the blastocyst implants; helps mediate immunological reaction

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16
Q

What is the placenta?

What is the difference between the fetal and maternal part?

A

Fetomaternal organ responsible for protection, nutrition, respiration, excretion of waste products, and hormone production

Fetal: formed by villous chorion, which project into the intervillous space containing maternal blood

Maternal: formed by decidua basalis, almost entirely replaced by the fetal part of the placenta (4th month)

17
Q

The placenta is the primary site of what?

Where do nutrients and waste materials travel?

When is the placenta and membranes expelled from the uterus?

A

Nutrient and gas exchange between the mother and embryo/fetus

Nutrients/O2 pass from maternal blood -> placenta -> embryo/fetal blood

Waste materials/CO2 pass form fetal blood -> placenta -> maternal blood

After birth

18
Q

____ will cover the entire chorionic sac until ____ week.

With growth, the villi associated with the decidua ____ become compressed and blood supply is reduced. These parts of the _____ will degenerate and leave an avascular bare area called the ____.

The remainder of the villi associated with the decidua ____ rapidly increase, branch, and enlarge and form a bushy area of the chorionic sac called the ____.

A

Primary chorionic villi; 8th

Capsularis; primary chorionic villi; smooth chorion

Basalis; villous chorion

19
Q

Chorionic villi invade the ____ and erode decidual tissue forming the ____.

Erosion produces ____. What do they do?

What do cotyledons contain?

What is the difference between the stem villi and the branch villi?

A

Decidua basalis; intervillous space.

Placental septa -> divides fetal part of the placenta into irregular convex areas or cotyledons

Main stem villi and multiple branch villi

Stem villi: villi that attach to the maternal tissues through the cytotrophoblastic shell

Branch villi: villi that grow from the sides of the stem villi

20
Q

As the embryo/fetus enlarges, the ____ bulges into the uterine cavity.

What forms a capsule covering the surface of the chorionic sac?

It thins and fuses with the ____ on the opposite wall and obliterates the uterine cavity.

A

Decidua capsularis

Decidua capsularis

Decidua parietalis

21
Q

When does the decidua capsularis degenerate?

Smooth chorion fuses with the ____ and obliterates the uterine cavity.

____ grows faster than the chorionic sac and fuse forming ____.

What is the fx of the membrane?

A

22-24 weeks

Decidua parietalis

Amniotic sac; amniochorionic membrane (membrane that breaks during “water breaking”)

Fuse with capsularis and adhere to parietalis

22
Q

When do the primary villi form? How?

When do secondary villi form?

A

End of 2nd week

Cytotrophoblast cells proliferate due to extraembryonic mesoderm and extend forming villi; core of cytotrophoblast cells covered by syncytiotrophoblast

3rd week: when extraembryonic mesoderm extends into the primary villi

23
Q

When does the tertiary villi form?

The core of the _____ is filled with capillaries.

Do secondary or tertiary villi have capillaries?

A

Develop when extraembryonic mesoderm differentiates into capillary and blood cells

Extraembryonic mesoderm (middle cytotrophoblasts covered by syncytiotrophoblasts)

Tertiary villi

24
Q

When does preeclampsia occur?

A

Occurs with reduced development of the branches of the chorionic villus tree -> lack of capillaries -> lack of gas exchange/hypoxia

25
Q

The branch of chorionic villi are bathed in _____ and are the site of ____.

Provide a large surface area for materials exchange across the ____.

A

Maternal blood; main gas exchange

Placental membrane

26
Q

What is contained in the placenta membrane before the 20th week?

After 20th week? What is this membrane called?

A

Syncytiotrophoblast, cytotrophoblast, CT of villi, endothelium of fetal capillaries

Syncytiotrophoblast, CT of villi, endothelium of fetal capillaries (no cytotrophoblasts) -> vasculosyncytial placental membrane

27
Q

In the 3rd trimester, nuclei in the syncytiotrophoblasts aggregate to form multinucleated protrusions called ____.

Towards the end of pregnancy, eosinophilic ____ thincken on the surface of the villi.

A

Syncytial knots

Fibrin or finbrinoids

28
Q

What is the histology of the placenta?

A

Fetal side: smooth and associated with the anmion

Maternal side: subdivided into lobes with villi and branches by decidual septa

29
Q

What does the early placenta contain?

What is in the core of the villus?

A

Trophectoderm shell comprised of inner cytotrophoblast and outer syncytiotrophoblast cells

Mesenchymal cells (fibroblasts) and fetal blood vessels

Hofbauer cells: phagocytic cells predominant in early pregnancy

Fetal RBCs are in early stages of hematopoiesis and can still have nuclei

30
Q

Huh

A

Jkj

31
Q

Late placenta contains _______ cells from trophectooderm shell. After 4th month of pregnancy, ____ cells decrease and become non-existent. ____ cells predominate and facilitate the maternal-fated exchange.

Late placenta also contains what?

A

Syncytiotrophoblast cells

Cytotrophoblast cells

Syncytiotrophoblast cells

Syncytial knots, hofbauer cells, fibrin/fibrinoids

32
Q

What is contained in the umbilical cord?

What are the two fetal circulatory shunts?

A

Two umbilical A and one umbilical V (vein contains oxygenated fetal blood, artery return deoxygenated fetal blood to placenta)

Ductus venosus: bypass liver

Ductus arteriosus and foramen ovale: bypass lungs

33
Q

What is placental accreta?

What causes this?

A

Abnormally strong and deep attachment of placenta to uterine wall

Due to previous uterine surgery or scar tissue following uterine curettage; increases in repeat C-sections

34
Q

What are the three forms of placental accreta?

A

Placenta accreta: placenta invades uterine wall but does not penetrate the myometrium

Placenta increta: placenta penetrates through myometrium

Placenta percreta: placenta extends through uterine wall and pierces uterine serosa and commonly attaches to bladder or rectum

35
Q

What is placental previa?

Types of placental previa?

A

Abnormal extension of the placenta over/close to internal opening of the cervical canal

Marginal placenta previa: margin of placenta lies close to internal cervical os

Partial placenta previa: edge of placenta extends across part of internal os

Total placenta previa: placenta covers internal cervical ostium

36
Q

What is a hydatidiform mole?

What is the difference of a partial vs complete mole?

A

Replacement of normal villi by dilated of hydropic (endematous) translucent vesicles

Partial: fetus forms; from meiotic nondisjunction or two haploid fertilizing sperm; capillaries carrying blood to mole are seen in the villi

Complete: paternal origin; no fetus; fertilization of blighted ovum by haploid sperm; avascular

37
Q

What is an invasive mole?

What is a choriocarcinoma?

A

Complete mole with increased local invasion; persistent high hCG; trophoblast invades uterine wall causing hemorrhage; responds to chemo

Highly invasive, metastatic tumor that arises from gestational chorionic epithelium; increase hCG with uterine enlargement; treat with chemo

38
Q

Twins that originate from two zygotes?

Twins that originate from one zygote?

A

Dizygotic: always have two amnion and two chorions, but chorions and placentas may be fused

Monozygotic: type of placenta and membranes depends on when the twinning process occurs ->
division of embryoblast: two amnion and single placenta, fusion of vessels
division of embryonic blastomeres: two chorions, amnions, placentas or implant close and have fused chorions and amnions