Repro Week 6 Flashcards
What are the two phases of the development
Prenatal (Before Birth) and Postnatal (After Birth)
Define the embryonic period and whole timeline
(Feeling Ill, Please Get Oranges)
- Fertilization to week 8
- Placenta develops
- All major adult organs develop
Weeks
1) Fertilization and Pre-implanation (Days 0-7)
2) Implantation (Days 7-14)
3) Primitive Streak (Days 13-14) and Gastrulation (Days 14-16)
4-8) Differentiation of 3 layers and Organogenesis (Days 21 - 56)
Define the foetal period and what are the four things that happen?
(Run Further My Son)
Week 9 to Birth
- rapid growth and weight gain
- further differentiation of refinement of body structure
- movements felt by mother by the 5th month
- survival if born prematurely 27- 28 weeks
What is the duration of pregnancy?
When is the due date for birth?
A) 38 weeks from zygote to birth, spread over three trimesters
B) 40 weeks
Week 1 Events (Sperm Capacitation)
What are the three things that happen to the sperm?
What are the two things that trigger capacitation?
- Removes the protein coating (acquired in the epididymis) on the sperm head
- Plasma membrane is reorganized to expose the binding sites on the sperm head
- Oestrogen and vaginal mucus triggers capacitation
- The sperm must spend several hours in the female reproductive tract just to have hyperactive motility
Week 1 Events ( Acrosome Reaction)
What are the two functions of the egg in this reaction
What causes the digestive enzymes to be released?
What are the two digestive enzymes released and what do they digest?
- ZP3 on egg plasma membrane stimulates the sperm
- The egg produces progesterone
- Increased intracellular calcium, which causes the release of digestive enzymes from the acrosome
- Hyaluronidase (cumulus cell penetration)
- Acrosin (zona pellucida digestion)
Explain Fertilization
Sperm binds to oocyte, through sperm binding receptors in oocytes plasma membrane
Differentiate between fast and slow polyspermy
Fast Polyspermy: Electrical block of oocyte plasma membrane, block sperm from attaching to membranes
Slow Polyspermy: release of cortical granules from inside the egg bind to sperm binding receptors and remove them, hardens the zona pellucida, no other sperm can enter
Name the three stages of Pre-Implantation Development
Clean My BackPack
Cleavage Stage
Morula Stage
Blastocyst Stage
Define the Cleavage Stage
Cleavage Stage (increasing cell number without cell size/ 2-8 cells)
Define the Morula Stage and describe the event that takes place
What junctions do?
a) Inner cells have what junctions?
b) Outer cells have what junctions?
Morula Stage (inner and outer cell populations formed/ 16-32 cells)
- Inner cells have gap junctions
- Outer cells have tight junctions
- Sodium pumped into the morula, which leads to a influx of water
Define the Blastocyst Stage and describe the two events that take place
a) Outer cells (differentiation) Trophectoderm
b) Inner cells (differentiation)
Blastocyst Stage (first cell differentiation event/ 64+ cells)
- Accumulation of water, forming the blastocoel cavity
- Outer cells in trophoblasts (CDX2) = trophectoderm differentiation (foetal placenta – chorion)
- Inner cells (OCT4) = inner cell differentiation (embryo proper)
- Rapid growth and enzymes hatching from zona pellucida
Explain the stages in Implantation
Adding is cool
A) Adherence: Protein-mediated binding of trophoblast to the endometrium, which secretes digestive enzymes and growth factors against it
B) Invasion: Trophoblasts grows into cytotrophoblast (cells in the inner layer) and syncytiotrophoblast (multinuclear cytoplasmic mass/digest and invade endometrium)
C) Completion: Blastocyst enveloped by endometrium
- Syncytiotrophoblast secretes hCG, directly stimulates Corpus to produce progesterone, maintaining pregnancy for 8-12 weeks
Explain how the foetal placenta is formed
a) What does the inner cell differentiate into? (2)
b) What does the out-pocket of hypoblast cells form?
c) Extra- embryonic mesoderm + Cytotrophoblast + syncitiophoblast = ?
inner cell mass differentiates into epiblast (amnion) and hypoblast (yolk sac) —> bilaminar embryonic disc
out-pocket of hypoblast cells form the allantois
Extra-embryonic mesoderm + Cytotrophoblast + syncitiotrophoblast —> chorion + chorionic villi —> beginning of the foetal placenta
Name each function of the extraembryonic membranes
A) Amnion
B) Yolk Sac
C) Allantois
D) chorion and chorionic villi
A) Amnion: protects the baby from physical trauma, maintains temperature, prevents fusion of embryonic structures, allows movement
B) Yolk Sac: brief nutrient support, source of early blood cells and vessels
C) Allantois: connective stalk that will eventually form blood vessels that makes up the umbilical cord
D) Chorion and chorionic villi: maternal decidua forms the true placenta
