L9 human embryology and developmental biology
8 important questions on L9 human embryology and developmental biology
When is the embryonic period?
And when the fatal period?
- week 3-8 - embryonic
- remaining 30 weeks - fetal
When is the prenatal period?
When is the pre-embryonic period?
- The 38 weeks between fertilisation and birth
- First 2 weeks development when zygote becomes spherical, multi-cellular structure.
What are the trimesters of pregnancy?
2nd = week's 14-26
3rd = week's 27 and on (38-40 weeks)
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How is the inner cell mass (ICM) also called in mammals? And what is it?
mammals, is the mass of cells inside the primordial embryo that, once fertilized, will eventually give rise to the definitive structures of the foetus.
What does the last fase of gastrulation consist of?
2. Chorda formation
Germlayer formation and movement during gastrulation
Mesoderm (intraembryonic) -> formed between epiblast and endoderm
Ectoderm -> formed during epiblast cells that stay on dorsal surface
So, all layers derive from epiblast cells!!!
Formation of the body axes - Week 3
What is the primitive node?
From what is the notochord formed?
Notochord -> is formed from primitive node and mesoderm.
- defines body axis
- is the site of the future vertebral column
- appears on day 16
- notochord also induces formation neuroectoderm and differentiation of motor neurons
What is differentiation?
And what is Induction?
progenitor cells differentiate into various cells which have specific structure and function
Induction:
some tissues affect the differentiation, and determine the differentiating orientation of another tissue.
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