Embryology Flashcards
What generates all 3 germ layers ?
The epiblast
What happens when the ectoderm thickens ?
The neural plate forms
What does the neural plate do ?
The neural plate thickens at the edges and these are known as neural folds. A neural groove forms and the neural folds move towards one another and fuse forming the neural tube.
What are the openings at each end of the neural tube called ?
The anterior neuropore and posterior neuropore.
What causes encephaly ?
Failure of the anterior neuropore to close
What is encephaly ?
Skull is not present and brains are open, brain tissue degenerates.
What causes spina bifida ?
Defects in the neural tube
What is spina bifida ?
In spina bifida then vertebral arches don’t form properly.
What is spina bifida occult ?
Many people have this, it occurs around L5/L6 region and is where the vertebral arch fails too close. Only sign may be a tuft or hair.
What is spina bifida cystica ?
Occurs when there is protrusion of the spinal cord and/or meninges through a defect in the vertebrae.
How can these conditions be prevented ?
Reduced Vit A intake and give Folic Acid supplements during pregnancy.
How are these conditions diagnosed ?
Amniocentesis
Ultrasound
Blood screening for AFP
What are the names of the 3 flexures that form to split the CNS of the embryo ?
The cephalic, the pontine and cervical.
What areas does the cephalic flexure split ?
The midbrain and hindbrain
What areas does the pontine flexure split ?
Areas of the hindbrain
What areas does the cervical flexure split ?
Hindbrain and spinal cord
What is hydrocephalus ?
The build up of CSF due to a blockage in the cerebral aqueduct usually. Can be genetic, due to infection or spina bifida.
Which cells divide to make up the cells of the CNS ?
Neuroepithelial cells
What do the neuroepithelial cells end up as ?
Ependymal cells
What are microglia made from ?
Mesenchymal cells
What do neural crest cells form ?
PNS and non-neuronal cells
What is Lissencephaly ?
A smooth brain caused by a defect in neuronal migration.
What is Polymicrogyria ?
Excessive numbers of small gyri
What is Microcephaly ?
Small brain. Can be due to a genetic cause, drugs or virus (Zika).
What is Porencephaly ?
Small pores form in the brain filled with CSF.
What is Schizencephaly ?
Large clefts or slits seen in brain usually genetic or can be cause by a stroke or infection in utero.
What is Diastermatomyelia ?
A spinal cord malformation where the spinal cord is split into two parts. A bony or cartilaginous process fixes the cord in place.
