12.8 Anatomy: Embryology 1 Flashcards
What proportion of babies are born with birth defects?
1:33 (heart most common)
How many cells are there at the Day 3 and Day 4 embryo?
What do we call these?
Day 3: 16 cells (morula)
Day 4: 58 cells (blastocyst)
What happens at day 5-10?
Implantation
What does the inner cell mass split into?
Epiblast (embryo) and hypoblast=bilaminar disc
What are the three germ layers? What are they derived from? What do they beecome?
From the epiblast
Ectoderm (NS, epidermis)
Mesoderm: blood, heart, kidneys, gonads, bones, muscles, CT
Endoderm: epithelium: gut and associated organs
What does the notochord induce? Where does it come from?
From the ectoderm, induces neural plate–>groove–>tube–>crest
What structures are formed by the neural crest?
What does a defect result in?
Face, ganglia, Schwann, melanocytes
Cleft lip/palate (1:1000)
What is the difference between mesoderm and mesenchyme?
Mesoderm: is one of three embryonic tissue types
Mesenchyme: shape and behaviour of cells (independent motile cells)
What is the mesoderm divided into? What structures are derived from these?
Paraxial
(8th pair of somiteres)
Dermis, axial skeleton, muscles
Intermediate
Urogenital system
Lateral
Body wall limb skeleton, pleura/peritoneum, BVs, heart, gut/resp wall
What does the somite split into?
Sclerotome
Dermomyotome
What does the dermomyotome split into?
Dermatome (dermis)
Myotome (axial and appendicular muscles)
What does the sclerotome become?
Axial skeleton
Where does the appendicular skeleton come from?
Lateral plate
When does limb development begin?
End of 4th week (mesoderm)
How does diplopodia occur?
Splitting of ectodermal ridge
