Neuroembryology

Question 1

Ectoderm, mesoderm, and endoderm important for Neuro

Answer 1

Ecto - CNS

Meso - notochord

Question 2

Before the notochord and once establish

Answer 2

Before, ectoderm produces factors that promote epidermis formation but inhibit neuroectoderm formation

Once established, notochord produces factors allowing midline ectoderm cells to become neuroectoderm by blocking other factors

Question 3

Neural plate formation

Answer 3

Neuroectoderm cells multiply forming a plate in response to cheimcal signals from underlying notochord

Question 4

Neural groove and fold formation

Answer 4

Neural plate folds inward flanked by 2 neural folds

Question 5

Neuropore formation

Answer 5

Neural folds fuse in area of 4-6th somites and close the groove…fusion occurs both ways and forms cranial (close 26) and caudal (close 28th) neuropore

Question 6

Lamina terminalis

Answer 6

Site of closure of rostral neuropore

Question 7

Neural tube

Answer 7

As the neural tube closes, it separates the ectodermal surface to give rise to CNS, ventricular system, and central canal

Question 8

Anencephaly

Answer 8

Failure of rostral neuropore to close…absenc eof brain hemispheres and only a rudimentayr brainstem

Question 9

Spina bifida

Answer 9

Failure of caudal neuropore to close…vetebral arches reamin unfused at L5 or S1 level

Occulta (mild)
Cystica (meningocele)

Question 10

Cells adjacent to the tube lumen do what?

Answer 10

Migrate away from luminal surface to accumulate in regions of the mantle layer (future gray matter)

Question 11

Alar and basal plate

Answer 11

Dorsal manlte layer - alar plate - cell bodies of dorsal horn sensory neurons

Ventral mantle layer - basal plate - cell bodies of ventral horn sensory neurons

Question 12

Marginal layer

Answer 12

Myelinated axonal process of mature neurons will become white matter

Question 13

Roof and floor plates

Answer 13

Roof plate (dorsally) and floor plate (ventrally) connect the right and left alar and basal plates

Plates respond to chemical signals from ectoderm and notochord

Roof plate will fuse with pia mater to form the choroid plexus

Question 14

Dorsal pole of spinal cord

Answer 14

Ectoderm cells produces factors which induce the roof plate cells to produce BMP4 and 7 to induce formation of sensory neurons

Question 15

Ventral pole of spijnal chord

Answer 15

Notochord releases SHH which induces floor plate ot release Shh to induce motor neuron formaiton

Question 16

Primary brain vesicles

Answer 16

prosencephaoln (fore)
Mesencephalon (mid)
Rhombencephaoln (hind)

Question 17

Secondary vesicles

Answer 17

Telen
Dien
Mesen
Meten
Lyelen

Question 18

Prosencephalon

Answer 18

Forebrain

Divides to telencephalon (striatum, cerebral cortex…lateral ventricles) and diencepaholon (hypothalamus and thalamus…3rd ventricle)

Question 19

Mesencephaolon

Answer 19

Midbrain

Becomes red nucleus and substantia negra…cerebral aqueduct

Question 20

Rhobencephalon

Answer 20

Hindbrain

Becomes metencephalon (pontine nuclei and cerebelumm…4th ventricle) and myelencephalon (medulla, inferior olive…4th ventricle central canal)

Question 21

Segmentation

Answer 21

As vesicles ontinue to form, notochord produces signaling molecules

Hindbrain forms 7 rhombomeres…serve as molecular framework for cranial nerve development

Question 22

Hox genes

Answer 22

Homeotic selector genes control the regional ID of vertebrate CNS and give each segment uniwue ID

Restricts cranial nerve growth to specific rhombomeres

Prevents axons from other cranial nerves from growing into adjacent rhombomeres

Question 23

Flexures

Answer 23

Cephalic - midbrain/diencepaholon…persists in adult as brainstem/forebrain bend

Cervical - hindbrain/spinal cord

Pontine - caused by proliferation of alar plate of the future pons pushing pontine region anteriorly

Question 24

Pontine flexure results in

Answer 24

Rostral medulla moving laterally and alar plate cells becoming lateral and migrating anterior to basal plate cells

Also enlarges the central cavitiy which will become 4th ventricle

Question 25

Choroid plexus develops from

Answer 25

Roof plate and overlying pia mater

Question 26

Cerebellum and pontine nuclei from

Answer 26

Cerebellum - from alar plate neuroblasts into the roof plate

Pontine - from the alar plate cells that have migrated to anteriro pons

Question 27

Cerebral aqueduct

Superior colluculus, inferior colliculus, red nucleus, and substantia negra formation

Answer 27

As midbrain walls thicken, narrowing of centra lcanal produces cerebral aqueduct

Alar plate cells migrating medially towards roof plate

Question 28

Entire diencephalon derived from

Answer 28

Alar plate

Question 29

Cnetral caivty of diencephalon formed from the

Answer 29

3rd ventricle

Question 30

Telencephalon from both the

Answer 30

Alar plate (mostly cortical cells) and the basal plate *basal ganglia)

Question 31

Majority of telencephaln is

Answer 31

White matter and neurons have migrated to area adjacent to the surface

Question 32

Lissencephaly

Answer 32

Smooth brain

improper neuronal migration

Could be from viral, insufficienct blood uspply, or gene mutations

Question 33

Hydrocephaly types

Answer 33

non-communicationg - caused by changes in CSF flow

Communicating by Overproduction or poor absorption

Question 34

Cranial meningocele and meningoencephalocele

Answer 34

A) meningnes and CSF in cyst

B) brain tissue but meninges in cyst through a bone defect

Question 35

Cerebral palsy

Answer 35

Infection, Insufficent O2

Spastic - hypertonia and spasticity
Ataxic - motor skills uncoordination and balance can be affected