L19 Neurulation and Embryonic Folding Flashcards
what are the common presentation for spinida bifida?
dimpled skin and a tuft of hair
how is neurulation initiated?
The notochord signals to the overlying ectodorm, to signal it to thicken and form neural-ectoderm (which gives rise to neural plate). this is called induction
DAY 19
what happens with neurulation on during day 20?
the lateral edges of the neural plate elevate to form neural folds.
Fusion of the neural folds begins in the cervical (neck) region of the embryo and continues cranially and caudally
what does the neural tube separate to form day 20?
As the neural folds fuse, the tube separates from the surface ectoderm
on what day does the anterior neuropore fuse?
day 25
on what day does the posterior neuropore fuse?
day 28
what do the cranial and caudal ends of the neural tube form?
cranial - brain
caudal - spinal cord
what is anencephaly and how is it caused?
failure of the anterior neuropore to fuse means the forebrain does not form, so the baby has no cognition, memory, speech, vision and hearing. there is normally a brainstem which controls heart, lungs and some reflexes.
how does the forebrain not form during anencephaly?
the open neural cord is exposed to the amniotic fluid/cavity, which damages the neural cord
how long does a baby with anencephaly survive?
rarely a few years but most are stillbirth or newborn dies a few hours after birth
what is rachischisis?
the spinal cord does not form properly leading to paralysis and the open neural tube prevents formation of vertebrae. the flat plate of neural tissue is exposed at birth so ther eis a high risk of infection
what is a NTD and which disorders are NTDs?
Neural Tube Defect. anencephaly and rachischisis are both NTDs. spina bifide is technically also a NTD but is actually due to abnormal induction of sclerotime by the notochord
how many births are affected by NTDs in the UK and how can this number be reduced?
1 in 1000 births in the UK and folic acid reduces NTDs by 50-70 %
(marmite is rich in folic acid)
where are the neural crest cells found?
they are at the lateral edges of the folds of the neural-ectoderm. once the neural tube forms the crest cells migrate laterally and ventrally though developing embryo, differentiating and contributing to the formation of many structures and systems
which structures are derived from the neural crest cells?
heart teeth skull bones glands eg adrenal nervous system in gut
