Embryology Flashcards
Derivatives of neural crest cells
Ganglia, schwann cells, adrenal medulla, melanocytes
Alar plate
sensory
Basal plate
motor
Mantle zone
grey
Marginal zone
white
TELENcephalon
cerebrum
DIENcephalon
eye cup
thalamus, hypothalamus, epithlamus
MESENcephalon
midbrain
METENcephalon
pons
cerebellum
MYELENcephalon
medulla oblongata
Signalling spinal cord
Upregulation FGF
Downregulation BMP 4
expression chordin and noggin
Nerual plate signalling
switches from E cadherin to N cadherin
When does the neural tube close?
Begins week 4
Anterior D25
Posterior D27
When does the eye begin to develop?
end of week 4 - day 22
What does the lens form from?
surface ectoderm - placodes
What do the layers of the optic cup form?
Outer - pigmented layers of retina
Inner - unpigmented / nervous layer
rim - iris and ciliary body
Optic nerve development
In seventh week
inner and outer layers stalk fuse
in 9th week becomes optic nerve
Where do the choroid and sclera come from?
mesenchyme surrounding the optic cup
Where does the conjunctiva come from?
inner layer of ectoderm
Signalling in eye development
PAX6 is the master signalling - expressed in anterior neural plate
SHH responsible for orbit separation - up regulates PAX2 in optic stalks and restricts PAX6 to optic cup and lens
Microphtalmia
eyeball too small - genetic condition/ IU infection/ FAS
Anophtalmia
absence of eye - genetic/infection
failure of optic vesicle to develop
Cyclopia
failure of prosencephalon to divide orbits - mutations in SHH
Coloboma iridis
Keyhole defect in iris - failure of choroid fissure to close
