Placenta And Fetal Membranes Flashcards
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.
Chorion, amnion, umbilical vesicle, and allantois
Placenta
Maternal and fetal bloodstreams
Umbilical cord
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?
Totipotent
Blastocyst; embryoblast; trophoblast
Polar trophoblast layer: direct contact with the embryoblast
Mural trophoblast layer: surrounding blastocyst cavity
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?
2 week
Embryonic; non-embryonic
Embryoblast; blastocyst cavity
Bilaminar embryonic disc; epiblast; hypoblast
Epiblast
Hypoblast: amniotic cavity, amnion, umbilical vesicle, connection stalk, chorionic sac
When is blastocyst implantation completed?
The ____ contacts the endometrium and diffentiates in two what two cell type? What are their fx?
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
What is an ectopic pregnancy?
Where does this occur?
Does it produce hCG?
What are the signs?
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
What is the amnion?
What is the fx of the amnioblasts?
Describe primordial uteroplacental circulation?
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
____ will eventually obliterate the chorionic cavity and forms the epithelial covering of the ____.
The umbilical cord came from the _____.
Amnion; umbilical cord
Connecting stalk
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?
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
What is hydramnios?
What are the clinical signs?
Excessive amniotic fluid
Genetic defect, fetal defect in CNS, or blockage of the GI tube
Abdominal pain, swelling, bloating, breathlessness
What is oligohydramnios?
What does this cause?
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)
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.
Closing plug
Extraembryonic mesoderm
Extraembryonic mesoderm; chorion
Hypoblast
Extraembryonic coelom
____ 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?
Extraembryonic somatic mesoderm; extraembryonic splanchnic mesoderm
Secondary umbilical vesicle (yolk sac)
Connecting stalk
Extraembryonic somatic mesoderm, cytotrophoblasts, and syncytiotrophoblasts
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?
End of 2nd week
Vascular, syncytial columns
Syncytiotrophoblasts; extraembryonic somatic mesoderm
Primary chorionic villi
8th week
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?
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
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?
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
What is the placenta?
What is the difference between the fetal and maternal part?
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)
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?
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
____ 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 ____.
Primary chorionic villi; 8th
Capsularis; primary chorionic villi; smooth chorion
Basalis; villous chorion
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?
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
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.
Decidua capsularis
Decidua capsularis
Decidua parietalis
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?
22-24 weeks
Decidua parietalis
Amniotic sac; amniochorionic membrane (membrane that breaks during “water breaking”)
Fuse with capsularis and adhere to parietalis
When do the primary villi form? How?
When do secondary villi form?
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
When does the tertiary villi form?
The core of the _____ is filled with capillaries.
Do secondary or tertiary villi have capillaries?
Develop when extraembryonic mesoderm differentiates into capillary and blood cells
Extraembryonic mesoderm (middle cytotrophoblasts covered by syncytiotrophoblasts)
Tertiary villi
When does preeclampsia occur?
Occurs with reduced development of the branches of the chorionic villus tree -> lack of capillaries -> lack of gas exchange/hypoxia
