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97 Cards in this Set
- Front
- Back
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From what do the fetal membranes develop?
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From the zygot
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What is fetal membranes relation to the embryo formation?
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Does not participate in the formation of the embryo
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What functions does the fetal membrane perform?
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Nutrition, respiration, excretion, protection
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What are the fetal membranes?
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Yolk sac, amnion, chorion, allantois
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When can we distinguish the primary yolk sac?
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8th day
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What kind of membrane covers the primary yolk sac + these cells arise from?
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Exocoelonic membrane (heusers membrane); trophoblast. Comes from Cells from hypoblast covering the blastocystic cavity
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When does the primary yolk sac become secondary yolk sac?
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9th-12th day
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What kind of cells covers the secondary yolk sac?
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Extraembryonic splanchnic mesoderm
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How is the yolk sac connected to the midgut?
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By a narrow yolk stalk
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What will the yolk stalk become later?
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Umbilical cord
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Where is the yolk sac located?
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Stays in the chorionic cavity
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What happens to the yolk sac by the end of second month?
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Detaches from the midgut loop by the end of the second mouth
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What happens to the yolk sac in 4th month?
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Yolk sac is very small and stops to exists as fetal membrane
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What is the significance of the yolk sac in 2nd – 3rd week?
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Transfer of nutrients to the embryo from trophoblast to embryonic disc
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What about the primordial germ cells in 3rd week?
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Gonocytes migrate from the wall of the yolk sac to the primodium of gonads (spermatogonia, oogonia)
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What other main functions of the yolk sac occur in 3rd week?
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Blood development – angiogenesis (extraembryonic mesoderm cells)
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When are blood vessels formed in the yolk sac?
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4-5 weeks
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What is the important significance of the yolk sac in 4th week?
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The endoderm of the yolk sac is incorporated into the embryo and forms the primitive gut
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What happens to the epiblast of the amnion at 8th day?
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amnioblasts
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What is the function of amnioblasts?
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To produce fluid
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What is the amniotic fluid composed of?
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99% water, proteins, glucose, hormones, inorganic salts
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How much amniotic fluid is secreted in different periods?
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10 weeks: 30 ml
20 weeks: 350 ml 37 weeks: 1000 ml |
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How does the circulation of the amniotic fluid look like in third trimester?
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The fluid turns over completely every 3 hours
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What happens to the water of the amniotic fluid during its circulation?
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Most of the water passes through the amniochorionic membrane into the maternal tissue fluid and enters uterine capillaries
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Where does the amniotic fluid end up?
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Swallowed by the fetus – at the end of pregnancy up to 400 ml per day
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How does the water return to the amniotic sac?
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Through the fetal urinary tract
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What are the functions of the amniotic fluid?
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Permits symmetrical external growth of the embryo and fetus. Amortization. Helps control body temperature of embryo. Development of the digestive and urinary tract.
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What happens to the amnion at 4th month?
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Amnion enlarges, obliterates the chorionic cavity and forms amniochorionic membrane
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What does the wall of the amnion form?
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Epithelial covering the umbilical cord
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How long is the umbilical cord?
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50 – 60 cm
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What is found inside the umbilical cord?
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Umbilical artery, umbilical vein and yolk stalk
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What happens to uterine cavity when amnion grows?
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Uterine cavity obliterates
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What build up the wall of the fetal sac?
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Decidua capsularis and parietalis. Smooth chorion. Wall of amnion
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What is the process where you take a small amount of amniotic fluid by a needle called? + When is this process done
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Amniocentesis 14th week
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What is interesting when examining the fluid and for what?( Amniocentesis)
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Fetal cells, for chromosomal defects
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What happens with the divertuculum from the wall of the allantois at 16th day?
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Extends into the connecting stalk
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What happens in allantois wall between week 3 and 5?
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Early blood formation
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What is formed by the blood vessels in the wall of allantois ?
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The umbilical arteries and veins
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What happens to allantois between 10th and 12?
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Degenerates
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What happens to the allantois later?
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It’s connected with urinary bladder, forms the urachus which after birth becomes the median umbilical ligament – around 10-12 week
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What does the chorion develop from?
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Trophoblast and extraembryonic mesoderm
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When does primary villi arise + What does it contain?
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end of week 2 – Trophoblast
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When does it become secondary villi?
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3rd week
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What do secondary villi contain?
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Trophoblast, extraembryonic mesoderm
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When does it become tertiary villi?
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From 4th week
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What is characteristic for tertiary villi?
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Blood vessels
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Describe the system of vessels supplying the fetus?
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Vessels in chronionic villi contact with vessels in the chorionic wall, then umbilical vessels in the connecting stalk and these contact with blood circulation system in the fetus
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Where is tertiary villi located in the 10th week? + now called
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In the embryonic pole - Vellus chorion
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What is the rest of the chorion called(not Vellus chorion)?
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Smooth chorion
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What morphological types of villi exist?
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Anchoring (stem) villi and floating (branch) villi
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What will the villus chorion later participate in?
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the fetal component of the placenta
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What is the decidua modified by?
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Modified by hormones (progesterone, estrogenes)
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From where does the decidua come?
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Endometrium of uterus
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What are the changes in the endometrium of uterus + name of change?
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Uterine glands degenerates.
The stromal cells enlarge, change their shape epithelioid, accumulates glycogen and lipids – called Decidual reaction |
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What are the names of the regions of the decidua?
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Deciduas basalis
Decidua capsularis Decidua parietalis |
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What are the diameter and the thickness of a mature placenta?
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Diamater: 15-20 cm Thickness: 3 cm
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What is the weight of a mature placenta?
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About 500 g
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How much of the internal surface of the uterus does it occupy?
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15-20 %
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How much blood is it in the intervillous spaces?
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150 ml
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In hemochordial type of placenta where is the villi bathed?,
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It’s bathed in maternal blood
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What are the parts of the placenta?
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Fetal part, Maternal part
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What builds up the placental membrane?
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Endothelium of villus capillary. Connective tissue of villus. Trophoblast
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How does the histological structure of the tertiary villus change?
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Degeneration of cytotrophoblast
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What are the waste products of the fetus?
How are they transported to the mother? |
CO2, urea, uric acid, bilirubin
Endometrial veins |
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What are transported to the fetus from the mother + how?
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Water, carbohydrates, aminoacids, lipids, electrocytes, hormones, vitamins, iron, antibodies –
transported througe Endometrial spiral arteries |
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What other substances take this way also to reach the fetus?
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Drugs, alcohol, CO, viruses, bacteries
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What are the functions of the placenta?
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Transport of gases. Transport of nutrients. Elimination of waste material. Endocrine secretion. Barrier to microorganism
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How much oxygen does the fetus take?
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20-30 ml oxygen/min
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How is oxygen transported in the fetus blood?
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Through fetal hemoglobin – HbF
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How thick is the placental barrier?
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2-5 micrometer
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How is the surface of the placental barrier?
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14-15 micrometer
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What is the placenta also permeable to other than oxygen and carbon dioxide?
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Carbon monoxide
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What cells of the placenta produce hormones?
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Syncytiotrophoblast
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What steroid hormones are produced + function?
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Estrogen and Progesteron -
Estrogen: uterus and vagina growth. At the end of pregnany increases uterus myometrial, contractile activity. Progesteron – essential of the maintance of pregnany |
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When does the secretion of progesterone begin?
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secreted from about 8th week
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What glycoprotein hormones are produced + function?
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Hcg and hCS -
Hcg – maintains the corpus luteum Hcs – carbohydrate metabolism in mother – fetus is ensured of an adequate glucose supply |
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What happens to the secretion of hCG after 8th week?
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Its secretion declines; pregnancy test
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What microbes are not stopped by the placental barrier?
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Rubella virus, cytomegalovirus, herpes simplex virus
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What does dizygotic pregnancy result to?
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Multiple pregnancy – Twins
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What does monozygotic pregnancy result to?
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One placenta, one chorion, one amnion
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What are HLA?
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Antigens in the plasma membrane of cells which are unique to each person
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How is HLA used by the immunological system?
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To differentiate self cells and non-self cells.
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What does the prostaglandin secreted by macrophages in villi and decidua do?
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, Inhibit activity of NK and Tc
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How does molecules on the trophoblast act?
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Inactivate local cellular immune response
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Where is α-fetoprotein produced?
How does it function? |
Produced in fetal yolk sac
Liver-caused immunosuppression of mothers immunological cells |
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What does the IgM of the fetus act on?
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Against mothers cytotoxic lymphocytes
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What hormones in blood of pregnant woman cause immunosuppression?
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Estrogens, Progesterone, hCG
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What immune response is especially suppressed?
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Cellular immune response
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What causes Rh incompatibility?
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Antigen D on the fetal erythrocytes present; mothers erythrocytes lack this antigens
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What is another name for Rh incompatibility?
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Hemolytic disease (erythrobastosis fetalis)
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What does erythroblastosis result to?
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Antibodies produced by mother go through placenta, cover fetal erythrocytes and destroy them causing hemolysis. Brain damage in addition to anemia
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High levels of a—fetoprotein indicates:
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neural tube defects
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lecithin/sphingomyelin ratio gives info about.
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the maturity of lungs
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The fetal (extraembyonic) membranes develop from:
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the zygote
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AMNION comes when from where?
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day 8 from AMNIOBLASTS (from epiblast)
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Oligohydroamnions is what + can lead to:
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low volumes of amniotic fluid
renal agenesis facial defect - Complications: pulmonary hypoplasia, limb defects e.g. club foot |
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Polyhydroamnions is what + can lead to:
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high volumes of amniotic fluid;
anencephaly esophageal atresia |
