Summary of Key embryonic events in week 1-8 Flashcards
Summarise the key events in Week 1 (the preimlantation stage)
- Fertilisation
- Embryo travels down the uterine tube
- Embryo undergoes clevage divisions as it is travelling
- Compaction occurs resulting in the formation of the morula (typically 16 cell stage) - the embryo is now in the uterus
- First differention occurs, whereby Blastocyst is formed - which is characteriszed by the first proper differentiation of the embryo into the trophoblast and the inner cell mass
- Blastocyst hatches from zona pellucida
Summarise the events of week 2
- Implantation occurs thanks to lots of cross talk between embryo and endometrium
- After implantation, bilaminar disc is formed (since the inner cell mass turns into the hypoblast and epiblast)
- Trophoblast turns into syncitiotrophoblast and cytotrophoblast
Summarise the key events of Week 3
- Gastrulation
- Formation of the notochord
- Formation of the neural tube
- Formation of the heart tube
Summarise the key events in Week 4
- Closure of neural tube
- Heart starts to beat
- Limb buds develop fro week 4 to week 8
- Face begins to develop
- Gut development
Approximately when does septation of the heart occur?
Weeks 5-7 heart septates and chambers are formed.
When do blood vessels start to appear?
Week 3
As he ectoderm of the trilaminar disc is folding to form the neural tube, the endoderm also starts to fold to form what?
When is this happening?
The gut
Week 3 -4
Essentially the dorsal part of the yolk sac forms the primitive gut
At what week do the trachea and lung buds appear? And from which gut structure does it arise from?
Week 4
Foregut
At what week do bronchopulmonary segments start to appear?
Week 6
The foregut, midgut and hindgut are all visible at which week roughly?
Week 3 - 4
Which is the first bone to ossify and when does it occur?
Clavicle, weeks 6-7
