Embryology Flashcards
what are the three layers of the derm layers?
ectoderm
mesoderm
endoderm
what layer of the term trilaminar plate forms the nervous system?
ectoderm
what layer of the term trilaminar plate forms the bone?
mesoderm
what layer of the term trilaminar plate forms the gut?
endoderm
what layer of the term trilaminar plate forms the lungs?
endoderm
what layer of the term trilaminar plate forms the epidermis ?
ectoderm
what layer of the term trilaminar plate is in contact with the yolk sac?
endoderm
at which week does the CNS start to appear?
3rd week
what is formed from the thickening of the ectoderm anterior to the primitive node?
neural plate
what causes the neural plate to form?
primitive node sends out signals
what are the thickened edges of the neural plate called?
neural folds
what day does the neural plate start to fold ?
day 20
where is the first area the neural tube starts to fuse?
in the middle
at what day does the anterior and posterior neuropore both close ?
day 27
what neuropore closes first?
the anterior or posterior
the anterior closes first at day 25
the posterior closes at day 27
what is another name for the anterior neuropore ?
the rostral
before the neural tube closes, is it in contact with amniotic fluid ?
yes
what is the depression down the neural tube called?
neural groove
what shape do the cells in the neural groove change from and to ?
columnar -> wedge shaped
what are the three main neural tube defects ?
Anencephaly
Encephalocoele
Spina bifida
what defect occurs during anencephaly ?
failure of the anterior neuropore closure
what would result in the anterior neuropore not closing?
the neural tube is in contact with the amniotic fluid so the skull and brain can’t form properly
can’t people with anencephaly survive?
no
- usually still birth
is anencephaly more common in males or females ?
x4 common in females
what defect results in encephalocoele?
when the rostral neuropore doesn’t close properly and cerebral tissue herniates through the skull defect
in what areas is the skull defect most common in encephalocoele?
occipital and fronto-nasal area
what common defects post birth does encephalocoele result in due to the areas of brain which is affected?
vision impairment and emotion and cognitive impairment
what do the degree of neurological deficits depend on ?
- part of brain affected
- area of brain affected
out of the three most known neural tube defects which one is most common?
spina bifida
is anencephaly and encephalocoele common?
no they are rare
what defect results in spina bifida ?
defect in the closure of the caudal (posterior) neuropore and the vertebral arches don’t fuse
are there different subtypes of spina bifida ?
yes three main subtypes
what are the three sub types of spina bifida ?
meningocele
meningomyelocle
myeloschisis
which of the three subtypes of spina bifida are most severe?
myeloschisis