Term
| Two components of the placenta |
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Definition
Fetal - villous chorion (outer membrane of gestational sac)
Mom - decidua basalis |
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Term
| Characteristics of the placenta at term |
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Definition
Diameter = 22 cm
Thickness = 2-2.5 cm thick
Weight = 450 g (1 lb) |
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Term
| What cells remodel the spiral arteries? |
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Definition
| EVT Cells from trophoblast |
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Term
| How are spiral arteries remodelled? |
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Definition
Replace displaced endometrium by the EVT cells; cannot maintain high BP to allow blood to flood intravillous space
KEY to how placenta works - need spiral artery remodeling, EVT cells allow blood to flood space |
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Term
| What is the embryonic structure at implantation? |
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Definition
| Blastocyst (fluid filled structure; day 7) |
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Term
| What is the TROPHECTODERM? |
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Definition
| Progenitor of trophoblast cell population - interacts with endometrium during implantation; forms various parts of placenta |
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Term
| What part of embryo interacts with endometrium during implantation? |
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Definition
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Term
| What part of embryo interacts with endometrium during implantation and becomes various parts of placenta? |
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Definition
| Trophectoderm (progenitor of trophoblast) |
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Term
| What forms from inner cell mass? |
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Definition
| ICM forms fetus; source of embryonic pluripotent stem cells |
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Term
| Has embryogenesis begun at blastocyst stage? |
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Definition
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Term
| What is the Implantation Hypothesis of Pre-Eclampsia? |
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Definition
| Belief that embryonic implantation is TOO SHALLOW, precipitates pre-eclampsia |
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Term
| At what pole of the blastocyst does it implant into endometrium? |
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Definition
| At TROPHOBLAST (trophectoderm) |
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Term
| 3 cell populations derived from trophoblast: |
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Definition
Cytotrophoblast
Syncytiotrophoblast
EVT Cells (remodel spiral arteries) |
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Term
| What day post fertilization does the blastocyst implant? |
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Definition
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Term
| When does the ICM change to become the epidermis, origin of amniotic cavity? |
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Definition
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Term
| Difference between epiblast and hypoblast? |
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Definition
Epiblast - large & columnar; forms embryo, amnion
Hypoblast - small; round; determine embryonic axis |
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Term
| When is hCG initially produced, and by what structure? |
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Definition
| By day 8; hCG produced by the syncytiotrophoblast |
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Term
| What part of the blastocyst forms the primary yolk sac? |
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Definition
| The HYPOBLAST - form Heusner's membrane which lines the blastocyst to form the primary yolk sac (exocoelomic cavity) |
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Term
| How is the secondary yolk sac formed? |
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Definition
Primary yolk sac = extracoelomic cavity (from hypoblast cells)
Extraembryonic mesoderm forms extracoelomic spaces in the primary yolk sac, extracoelomic spaces fuse to form extraembryonic coelom = CHORIONIC CAVITY |
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