Embryology 2 Flashcards
(24 cards)
What are neural crest cells
Specialised cells from lateral neurectoderm which migrate to enter the mesoderm
What is the facial skeleton derived from
Neural crest cells of the 1st pharyngeal arch
What is the facial primordia derived from
1st pharyngeal arch
Frontonasal prominence
What is the stomatodeum
Depression in embryonic face with buccopharyngeal membrane at centre
It is between the FNP and maxillary and mandibular prominences
What is a placode
Ectodermal thickening that gives rise to an organ of special sense
Describe nose development
Nasal placodes on FNP invaginate to form nasal pits with medial and lateral nasal prominences
Maxillary prominence growth pushes nasal prominences towards midline
Maxillary prominences fuse with medial nasal prominences
Medial nasal prominences fuse with each other a the midline
This forms the intermaxillary segment
What is the intermaxillary segment composed of
Labial - philtrum
Upper jaw - incisors
Palate - primary palate
Describe formation of the definitive palate
Palatine shelves grow down from maxillary prominences on each side of the developing tongue
Mandible grows so tongue drops
Palatine shelves grow towards each other and fuse at the midline
Nasal septum grows down to fuse with the palatine shelves
What is a lateral cleft lip
Failure of fusion of medial nasal prominence and maxillary prominence
What is a cleft palate
Failure of fusion of palatine shelves
Fate of FNP
Forehead
Bridge of nose
Medial and lateral nasal prominences
Fate of medial nasal prominence
Philtrum
Primary palate
Mid upper jaw
Fate of lateral nasal prominence
Sides of nose
Fate of maxillary prominence
Cheeks
Lateral upper lip and jaw
Secondary palate
Fate of mandibular prominence
Lower jaw and lip
Describe eye development
Optic vesicles (from forebrain - diencephalon) grow and contact optic placodes
Optic placodes invaginate and pinch off
Placode becomes lens and vesicle becomes retina
Where do eye primordia initially form
Why does this need to change
Initially on side of head
Growth of facial prominences push eyes to front to give binocular vision
What is binocular vision
Overlapping fields of view
What is the EAM derived from
1st pharyngeal cleft
What are the auricles derived from
Proliferation of 1st and 2nd pharyngeal arches surrounding the EAM
Describe internal ear development
Invagination of otic placodes creates auditory vesicles
These vesicles develop into the membranous labyrinth (cochlea and canal system) to give hearing and balance sense
Describe external ear development
Initially in neck
Growth of mandible causes ascent of ears to the side of the head in line with the eyes
What can alcohol cause if it crosses the placenta and why
Fetal alcohol syndrome
Alcohol related neurodevelopment delay
Alcohol affects neural crest migration and brain development
Features of FAS
Thin upper lip Short nose Smooth philtrum Small head Low nasal bridge Small eye openings Underdeveloped jaw Flat midface
