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34 Cards in this Set
- Front
- Back
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Embryos enter the uterine cavity at what stage, how many days after fertilization?
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Morula state, 2-3 days after fertilization
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When does implantation begin?
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6/7th day after fertilization
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What is the temporal window of endometrial maturation during which the trophectoderm of the blastocyst can attach to the endometrial epithelial cells and subsequently can proceed to invade the endometrial stroma?
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Uterine receptivity
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What are the days of the window of implantation in humans?
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Days 20-24
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Before the embryo can implant, what must happen?
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It must hatch and expel the zona pellucida
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The endometrium consists of what 2 layers?
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1. Basilis layer - basal 1/3 of full thickness endometrium (not shed)
2. Functionalis layer - top 2/3 of full thickness endometrium (shed during menses) |
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What are the 2 main phases of menses?
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1. Proliferative phase - orchestrator of cellular proliferative activity
2. Secretory Phase - no change in thickness, differentiation of epithelial and stromal cells |
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What hormone is very important for the proliferative phase?
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Estrogen
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What hormone is very important for the secretory phase?
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Progesterone
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What happens if no pregnancy occurs?
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1. Regression of the corpus luteum
2. Functionalis layer breakdown results in menses |
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What are the minimal endocrine "needs" for normal cycling of the endometrium?
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Sequential exposure of estradiol and progesterone
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During IVF, what is the purpose of giving a GnRH antagonists?
(make sure its atagonist) |
Shut of HPG axis, take control of the cycle
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Is the human embryo good at attaching?
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Yes, very adhesive and invasive
Can attach almost anywhere |
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Is the endometrium always receptive?
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NO, defined period when the embryo can adhere and successfully implant
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What hormone is critical in the development of the receptrive endometrium?
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Progesterone
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What maintains the early pregnancy?
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hCG --> acts on corpus luteum and maintains estrogen and progesterone levels
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What is the window of implantation?
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Day 19/20-24 (middle of secretory phase)
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At what stage of the embryo development does implantation occur?
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Blastocyst
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How can a "5" or 3 cell embryo exist?
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Asynchronous cleavage
If dysynchrony >1, fetus aborts |
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The embryo becomes fully embedded in the endometrium by what day following the initiation of implantation?
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Day 7 (day 12-14 after ovulation)
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What are the 4 phases of human implantation and placentation?
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1. Apposition
2. Adhesion 3. Intrusion 4. Invasion |
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What is apposition?
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The hatched blastocyst is positioned in appostion to the endometrial epithelial cells
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What is adhesion?
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The trophoblast cells adjacent to the ICM adhere to the apical surface of the endometrial epithelial
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What is intrusion?
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The trophoblast cells insinuate themselves IN BETWEEN the endometrial epithelial cells
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What is invasion?
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The trophoblast cells and, ultimately, the whole embryo invade through the basemen membrane and the endometrial stroma and reach and invade into the maternal vessels
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What physiologic characteristic promotes proliferation and invasion?
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Low O2
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What molecules are thought to play an important role in invasion/adhesion?
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Cell adhesion molecules (CAMs)
ECM plays a role in invasion and remodeling |
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Implantation usually occurs where?
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At the mid posterior endometrial surface
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What are 2 specific enzymes thought to be involved in implantation?
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1. MMP-9
2. Urokinase type plasminogen activator |
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What is comparision of the trophoblast invasion to cancer NOT a good comparison?
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Because trophoblast invasion is a regulated process with specific factors involved in triggering and arresting the process
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What is a good way to picure the chorionic villi of the placenta?
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As the branching roots of a tree embedded in the endometrium and "bathed" in maternal blood
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What are the mitotically active progenitor trophoblast cells, which give rise to the terminally differentiated syncytiotrophoblasts?
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Cytotrophoblasts
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What are the 2 main functions of the trophoblasts?
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1. Endocrine function - hCG and P4 (and E) secreted mainly by synchytiotrophoblast
2. Exchange of nutrients and gases between mother and fetus |
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What may be critical in fetal development and has been implicated in the development of both maternal and fetal complications later in pregnancy?
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Extent of trophoblast invasion
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