Neurulation Flashcards
When does the epiblast migrate through the primitive streak
3 weeks
What does the endoderm give rise to?
Epithelial linings of resp. tract and digestive system, GI glands and glandular cells of liver and pancreas
What derivatives come from the mesoderm?
Skeletal muscles, blood cells, the lining of blood vessels, smooth muscle, trunk Ct, most of CV system, notochord
What is the ectoderm derived from?
Epiblast
What is the mesoderm derived from?
Epiblast that penetrated the primitive streak
What are the derivatives of the ectoderm?
Epidermis of the skin, epidermal derivatives, CNS, PNS, neural crest cells, eyes, internal ears
What is the notocord made of
Primitive pit and mesodermal cells
What induces ectoderm to become the neural plate?
Notochord
Surface ectoderm forms what?
Epidermis
Neuroectoderm forms the
Neural plate and neural crest
What is neurulation
The process by which the notochord, neural plate and neural crest become distinct
What acts as a hinge for neurulation
Neural groove
Where does the neural plate begin to fold
Lumbar area up
What does the neural tube arise from
Mesenchyme
What is the process of forming the neural tube called?
Secondary neurulation
Where does secondary neurulation occur?
The level of the sacral vertebrae
What do the mesoderm of the head and neck come from?
The neural crest
Defects in the folding of the neural tube at S1 S2 S3 typically manifest as what
Congenital heart defect
What is the most common closure deficiency
Congenital heart issues
Goldenhar syndrome is characterized by what
A neurocristopathy where incomplete closure of the mouth and nose area, ocassionally causes the mouth to be shifted
What is TCS
A neurocristopathy disorder which cases the face of a person to have sunken in eyes and a mouth that projects anteriorly
What is hirschsprung disease
Neurocristopathy in which patients have megacolon
What is craniosynostosis
Neurocristopathy in which patients have an anterior projecting forehead
What is micrognathia
Neurocristopathy in which a jaw is small or lacking
What is piebaldism
Neurocristopathy in which areas of melanocytes have no pigment
What do the meninges develop from
Neural crest cells and mesenchyme
When do the meninges migrate to surround the cns? What does this form?
20-35 days, primitive meninges
What do the primitive meninges differentiate into
Ectomeninx and endomeninx around 34-48 days
What happens between 45-60 days
Ectomeninx becomes more compact and forms spaces for future venous sinuses
Endomeninx becomes more reticulated and suharachnoid space appears
What dissociates giving rise to the epidural space
Spinal ectomeninx
How does the neural tube close and what do they form
Initiated at 5 sites and goes in both directions; cranial and caudal neuropore
What does a closure defect at closure 5 cause
Spina bifida
What is a defect at closure 2
Anancephaly
What is a defect at closure 1
Craniorachischisis
What is encephalocele
When parts of the brain go into a sac behind the head
What is meroencephaly
Acrania, from the lumbar portion up the spinal cord is open
What is cranioachischisis
When the spinal cord is open from sacral region up
What is spina bidfida oculta
When the neural arch doesn’t close completely
These patients have a tuft of hair above this area
What is meningocele
Where there is a sac filled with CSF extending from a portion of the spine
What is meningomyelocele
Meningocele but with the spinal cord in that sac
What is myeloschisis
Where the spinal cord is hemisected and open to the skin
When does head and tail folding begin
Week 4
What happens during the head fold
Neural folds project dorsally into the amniotic cavity
Neural folds grow cranially into oropharyngeal membrane and overhang the primordial heart
Forces translocation of septum transversum, primordial heart, peridcardial coelom to ventral surface
What forms the future anus
Cloacal membrane
When does the umbilical cord form?
After dorsal/ventral folding and lateral folding
When does the abdominal wall fuse
Lateral folding
What are some anterior body wall malformations
Omphalocele - bowel in membranous sac
Gastroschisis - bowel is exposed and protruding through body wall
Ectopia cordis - heart outside the rib cage
What is the pentalogy of cantrell
Anterior body wall malformation Needs -midline abdominal defect -anterior diaphragmatic hernia -cleft strenum -pericardial defect -intercardiac defect
