L6 - MSK - Fertilization and Gastrulation Flashcards
What happens within Week 1?
Formation of the inner cell mass
What happens within Week 2?
Formation of epiblast and hypoblast
What happens in Week 3?
Gastrulation
Where are the mitochondria on the sperm?
Middle Piece of Tail contains Mitochondrial sheath
What covers the nucleus of the Sperm?
Acrosome
What contains enzymes which are used to get into egg?
Acrosome
What contains the follicular cells of the egg?
Corona Radiate
What is Step 1 of Fertilization?
- Capacitation: Glycoprotein coat and seminal plasma proteins removed from plasma membrane of sperm. - Passage of sperm through corona radiata - Hyaluronidase
What is Step 2 of Fertilization?
Penetration of Zona Pellucida - esterases, acrosin ** , neuramindase - Zona Reaction - block polyspermy
Where does Fertilization occur?
Fallopian Tube
Where does Blastocyst form?
Uterus
What is Step 3 of Fertilization?
- Fusion of plasma membranes of oocyte and sperm - Head and tail of sperm enter oocyte cytoplasm
What is Step 4 of Fertilization?
- Completion of second meiotic division - Formation of male pronucleus - Fusion of male and female pronuclei
What are the results of fertilization?
1 - Completion of 2nd meiotic division 2 - Restoration of diploid number of chromosomes (46 chromosome!) 3 - Determination of chromosomal sec of embryo 4 - Metabolic activation of oocyte 5 - Initiation of cleavage
What occurs during Cleavage?
- Increase in cell number, but decrease in cell size - Embryo size Unchanged - Morula development (Day 3) *Occurs ~30hrs after fertilization
When does a Blastocyst form?
Day 5-7
How many layers are present at the end of week 1?
One layer. Inner cell mass (ICM)
What is the Trophoblast? What week does it occur? What does it give rise to?
Early pregnancy factor Week 1 Gives rise to: Cytotrophoblast Syncytiotrophoblast
What is the Cytotrophoblast?
Triggered by Trophoblast Week 1 - stem cell layer - mitotically active
What is the Syncytiotrophoblast?
Triggered by Trophoblast Week 1 - Proteolytic Enzymes, chorionic gonadotropin - Responsible for implantation and initial signal of pregnancy
What are 3 types of Assisted Reproductive Technologies?
- In Vitro Fertilization and Embryo Transfer 2. Cryopreservation of Embryos 3. Intracytoplasmic sperm Injection
What are Embryonic Stem Cells?
- Derived from the inner cell mass - Pluripotent : form virtually any cell or tissue type - Therapeutic cloning or somatic nuclear transfer
What forms when there is abnormal trophoblastic proliferation and excessive amounts of hCG produced?
Hydatidiform Mole
A Complete Hydatidiform Mole results from?
- Fertilization of an empty oocyte, followed by duplication of the sperm 2. OR from fertilization of an empty oocyte by two sperm

