development Flashcards
when does gastrulation occur? what is the outcome?
- the third week
- three layers are formed
during gastrulation, what cells are migrating and ultimately form all three layers?
epiblast
what gives rise to the CNS?
neural tube
what gives rise to the PNS?
neural crest
what are the neural derivatives of the neural crest?
- posterior root ganglia
- sympathetic chain ganglia
- prevertebral ganglia
- enteric ganglia
- para ganglia of CN 7,9,10
- sym ganglia of CN 5,7,8,9,10
what are some non neural derivatives of the neural crest?
- schwann cells
- melanocytes
- pia and arachnoid of the meninges
hirschprung disease is due to what?
-failure of migration of parasympathetic ganglion from cells from the neural crest
what are the three primary brain vesicles?
- proencephalon(forebrain)
- mesencephalon (midbrain)
- rhombencephalon(hindbrain)
on the fifth week, the three primary brain vesicles divide into what five secondary brain vesicles?
- Telencephalon (forebrain)
- Diencephalon (forebrain)
- mesencephalon (Midbrain)
- Metencephalon (hindbrain)
- Myelencephalon (hindbrain)
what are the four flexures?
- Cervical: between hindbrain and spinal cord
- Mesencephalic: bend in neural tube at the level of mesencephalon
- telencephalic: between the diencephalon and telencephalon
- Pontine flexure: divides the hindbrain into metencephalon and myelencephalon
the telencephalon expands to form what?
cerebral hemispheres
metencephalon gives rise to what?
- pons
- cerebellum
the diencephalon gives rise to what?
- thalamus
- hypothalamus
- optic cup
the myelencephalon gives rise to what?
-medulla
what is the process of forming the neural tube from the neural plate called?
neurulation
what initiates the formation of the neural tube?
-notochord formation during gastrulation induces formation of neural plate, which then starts the development of the neural tube
what is the first step of neural system development?
formation of the neural plate
what pathology results from failure of the rostral end of the neural tube (anterior neuropore) to close?
anencephaly
what pathology results from failure of the posterior neuropore to close?
myeloschisis
what is cranioshisis?
failure of the back of the skull to close
what is meningocele?
the cyst structure from failure of the back of the skull to close contains meninges
what is meningoenchephalocele
the cyst structure from failure of the back of the skull to close contains meninges and the brain
what is meningohydroencephalocele?
the cyst structure from failure of the back of the skull to close contains meninges, brain, and part of the ventricular system
what is the alar plate in the developing spinal cord?
- posterior cell masses that become the dorsal horn
- sensory
what is the basal plate in the developing spinal cord?
- anterior cell masses that become the ventral horn
- motor
what develops in the intermediate zone of the spinal cord?
the sympathetic nervous system
what is the sulcus limitans?
the groove that separates the alar and basal plates
how are the alar and basal plates arranged in the brainstem?
-the alar plates rotate dorsolaterally to give the plates a medial to lateral orientation
the alar and basal plates, which one has afferent fibers and which one has efferent?
Alar-afferent
Basal-efferent
what does the cerebellum arise from?
rhombic lip
what is dandy-walker syndrome? what would the CT show? what are the clinical signs?
- dilation of the fourth ventricle, incomplete development of midline portion of cerebellum
- CT shows enlarged posterior fossa with a midline cyst
- developmental delay, big head, hydrocephalus
what is chiari malformation? what is the difference between I and II?
- herniation of the cerebellar vermis and tonsils through the foramen magnum
- skull is abnormally small and compresses brain downward
- type I: develops as the skull and brain are growing
- type II: malformation is present at birth
what is prosencephalization?
differentiation of prosencephalon into the diencephalon and telencephalon
what is holoprosencephaly? what is the difference between alobar and semilobar?
- failure of prosencephalon to undergo cleavage
- Alobar: no lobes, single forebrain ventricle
- Semilobar: partial separation
fetal alcohol syndrome is associated with what?
holoprosencephaly
what is lissencephaly? pachygyria? micrgyria?
Lissencephaly: no gyri formed
Pachygyria: excessive gyri growth
Microgyria: deficient gyri growth
what are some signs of fetal alcohol syndrome?
- short
- low body weight
- small head
- mental retardation
- hypertelorism (eyes far apart)
what is the consequence of defective development of cerebral aqueduct?
- aqueduct stenosis
- hydrocephalus
what do radial glia do?
-they act as cell guides to allow neuroblasts to migrate away from the luminal surface and develop the layers of the cerebral cortex.
what is the difference between spina bifida occulta and spina bifida aperta?
occulta: skin is intact, marked by a patch of hair
aperta: skin is not closed over the vertebral defect
what is spina bifida?
-failure of vertebral arches to close
what is meningocele?
-spina bifida and meninges and CSF
what is meningomyelocele?
-spina bifida and meninges and CSF and spinal neural tissue
what should moms take to prevent spina bifida?
folic acid
what are the common diseases that can cause congenital nervous system defects?
T-toxoplasmomsis O-other agents(HIV, syphilis) R-rubella C-cytomegalovirus H-herpes simpex virus
Zika virus has been associated with what in newborns in america?
microcephaly
