When is it most likely for something to go wrong in human development?
The first 8 weeks (aka the embryonic trimester)
When does the Obstetrical calendar start? When does the calendar assume fertilization occurs?
Obstetrical Calendar starts 1st day of LMP
Fertilization starts 14 days after 1st day LMP (Approximates with ovulation, assumes the earliest possible point for fertilization)
Where does the Ovulatory Calendar start?
Fertilization (Two weeks after the obstetrical calendar starts)
What is the Zona Pellucida made of?
Where does most fertilization occur?
The Ampulla (distal 1/3 of the fallopian tube)
What all occurs in week 1? (5 things)
3. Blastocyst formation
4.Inner Cell Mass (Embryoblast)
What is another name for the inner cell mass?
What is capacitation?
What does this allow for?
The removal of a glycoprotien coat and seminal plasma protiens from the plasma membrane of the sperm for fertilization
-passage of sperm through corona radiata
The Acrosome Reaction
What does a sperm use to penetrate the corona radiata?
What does a sperm use to penetrate the zona pellucida?
Esterases, acrosin, and neuraminidase
What does the Zona Pellucida do to prevent polyspermy?
Changes conformation - the meshwork becomes rigid
What technique might be performed to induce pregnancy in a couple for which the male has a low sperm count?
Intracytoplasmic sperm injection
Make up for the diminished liklihood of a sperm contacting an egg by directly injecting the sperm into the egg.
Going from exterior to interior, what are the layers of a human oocyte?
- Corona Radiata
- Zona Pellucida
- Perivitelline Space
- Plasma membrane of oocyte
- Cytoplasm of oocyte
What does the perivitelline space assist in?
What does it do?
The zona reaction
Releases granules to block polyspermy
What is the name of the cell that divides in cleavage?
When does cleavage begin to occur?
At about 30 hours
When does the dividing embryo become a morula?
When does the embryo become an early blastocyst?
What changes to make this structure?
A fluid filled cavity (blastocystic cavity) is formed
When does the embryo enter the uterine body?
When does implantation typically occur?
Around day 6
What stage is the developing embryological structure in by day 7 (end of week 1)?
What are the main structures of this structure?
Inner cell mass, blastocyst cavity, and trophoblast ring
What two structures does the trophoblast give rise to, and what do those structures do?
This is a mitotically active stem cell layer, forms the syncytiotrophoblast. Stays on the outside
Contains proteolytic enzymes and hCG - responsible for implantation and initial pregnancy signaling.
Conceptually, the trophoblast gives rise to the placenta.
What does the inner cell mass give rise to?
Where do we get Embryos for Stem Cell Therapy?
From Cryo-preserved embryos
At what point does the Zona Pellucida disappear?
What this called?
By day 7
"Hatching of the embryo"
What immunosupressant protien to the trophoblasts produce?
When do we start to see this be produced?
Early pregnancy factor
After about 10 days
What is Hydatidiform Mole?
What causes the complete version?
What causes the partial version?
Abnormal proliferation of trophoblasts.
Complete: An empty oocyte getting fertalized, and then duplicating the sperm OR an empty oocyte getting fertalized by two sperm
Partial: Normal egg fertalized by two sperm
What would you call a malignant tumor which has developed from a hyatidiform mole?
Where do these types of tumors like to metastasize? (6 places)
What are the clinical features of Hydatidiform Mole?
- Vagnial Bleeding (villi can sometimes be seen)
- Pressure or pain of the pelvis
- Enlarged Uterus
- Hyperemesis Gravidarum
- Excess hCG
What two structures make up the Week 2 Inner Cell Mass?
Epiblast and Hypoblast
(In week 2 the inner cell mass differentiates into the epiblast and hypoblast)