Embryonic development of the nervous system W1 Flashcards
what is gastrulation and when does it occur
embryo transforms into multidimensional structure, occurs in week 3
what occurs in gastrulation
cells secrete different proteins and factors in a concentration gradient
thickened band of cells at tail end - primitive streak
endoderm between bilaminar layers becomes the mesoderm
what occurs after gastrulation? what week?
neurulation
week 3
what occurs during neurulation
thickens to form neural plate, then forms neural cord. edges elevate and pinch up forming neural groove containing neural crest cells
what forms during week 4?
neural tube forms from neural tube bending
cranial development in week 4?
3 primary brain vesicles:
-forebrain
-midbrain
-hindbrain
cranial development in week 5?
5 secondary brain vesicles:
-telencephalon
-diencephalon
-mesencephalon
-metencephalon
-myelencephalon
myelencephalon composed of?
medulla
metencephalon composed of?
pons and cerebellum
mesencephalon composed of?
midbrain
diencephalon composed of?
eye cup, thalamus, hypothalamus, epithalamus
telencephalon composed of?
cerebrum
when does gyrification occur
between week 10 and 40
name for abnormal closure of the neural tube at the spinal region?
spina bifida
name for failure of neural tube closure at the cranium?
anencephaly
what causes neural tube defects and why
folate deficiency - folate is needed to produce RNA and DNA
maternal hypothermia - impairs division of cells
sodium valproate (anti-epileptic)
teratogens
3 types of spina bifida?
spina bifida occulta - mildest and most common
meningocele - sac protruding from spinal column
myelomeningocele - sac containing spinal cord protrudes from spinal column (most serious)
what are teratogens?
substances that cause congenital disorders in a developing embryo or fetus
what do neuroepithelial cells of the neural tube walls divide and differentiate into
neuroblasts -> neurones
gliablasts -> oligodendrocytes, astrocytes
examples of what neural crest cells give rise to?
sensory ganglia and neurones
autonomic neurons
Schwann cells
melanocytes (in skin)
odontoblasts (in teeth)
meninges
what is Hirschsprung Disease and how does it occur
congenital megacolon
failure of neural crest to migrate and form parasympathetic structures in the colon
what are phaeochromocytomas? what are they a rare cause of?
tumour of the chromaffin cells of the adrenal glands (neural crest origins)
rare cause of adrenergic storm due to overproduction of adrenaline and noradrenaline
what type of conditions does failure of neural crest cell migration cause?
autonomic conditions
