When does most neuronal production and migration occur?
•third through fifth months of development•
The formation of neural connections (neuropil) and production of myelin sheaths continue after birth
When does gliogenesis take place?
during the second and third trimesters of pregnancy and early postnatal development
What does the mesoderm provide to the ectoderm
what is required for formation of the neural plate?
What does the plate come from
What is neurulation?
What does it involve?
process of forming the neural tube from ectoderm
–1) Formation of a neural plate
–2) Neural plate becomes neural groove surrounded by crests
–3) Groove becomes closed neural tube in highly ordered fashion
What does spina bifida result from?
Incomplete caudal neural tube closure
What does anencephaly result from?
What is something that may prevent this?
Incomplete rostral neural tube closure.
What does the neural tube develop into?
What are the3 vesicles that develop into the future brain?
Prosencephalon of forebrain
Mesencephalon of midbrain
Rhombencephalon of hindbrain
What are the flexures composed of, (structures)
What are the 5 secondary vesicles after seperation?
- –Cephalic flexure bet. Mesencephalon and prosencephalon
- –Cervical flexure bet. Rhombencephalon and spinal cord
- –Rhombencephalon sep. to metencephalon and myelencephalon at level of pontine flexure
- –Prosencephalon sep. to diencephalon and telencephalon
Talk through the specific structures that arise from each vesicle.
See slide 16 to check yourself.
Cerebral cortex, basa ganglia
thalamus, hypothalumus, retina
What does the lumen of the neural tube become?
What is the choroid plexus?
•Choroid plexus is vascular tissue + pia + ependymal cells
–Not in aqueduct nor spinal cord
What forms the C shape of the brain?
cortical development around the insula
What are the two signaling systems that pattern the dosoventral axis?
Sonic hedgehog (Shh) = secreted signaling molecule; initially expressed in the notochord (N)- planar signaling
Bone morphogenetic proteins (BMPs) = secreted signaling proteins with a variety of functions; expressed in ectoderm (ECT)- lateral signaling
Shh = ventral; expressed in notochord and floorplate (F)
BMPs = dorsal; expressed in epidermis
What happens once the nural tube is closed?
Once the neural tube is closed, the roofplate expresses one signal and the floorplate expresses a second signal. These signals are responsible for patterning dorsal and ventral regions of the spinal cord, respectively.
What is the Bell-Magendie law?
What does the mantle zone become?
Where do neurons start out?
Mantle zone becomes gray matter,
marginal zone becomes white matter.
Neurons start out in the ependymal zone (also known as the ventricular zone). Mantle zone is also known as the intermediate zone. Ependymal zone becomes less populated as neurons move out. Use this to desribe how you work your way out.
Progenitors become radial glia and then can develop into either neurons or glia.
Both neuroepithelial and adial glia are considered pluripotent.
At what point in development is it decided wether a cell will become a neuron or a glia?
Where does Adult take place?
In the formation of the brainstem: myelencephalon, what does the roof plate form?
ependymal.... choroid plexus
sensory nuclei for CN VII-X
motor nuclei or CN VII-XII
Metencephalon forms two divisions, what are they and what do they become?
1)Dorsal division looks like medulla
A)Alar plate forms cerebellum
1. Develops from Rhombic Lip
B)Sensory Cranial Nuclei (V)
2) Ventral division, basal pons contains pontine nuclei. This doesn’t follow typical dorso-ventral patterning
What does the mesencephalon form?
Alar plate of the mesencephalon forms the corpora quadrigemina
(Inferior colliculi and Superior colliculi)
GSA of CN V is another alar-derived nucleus
Basal plate of the mesencephalon forms GSE and GVE of CN III
GSE of CN IV
What does the diencephalon form?
Alar plate is largely thalamus
Basal plate is largely hypothalamus
Roof and alar plates give rise to epithalamus (habenula and pineal)
Optic cup, another derivative, becomes CN II
What are the two waves of formation for the telencephalon?
Initial pattern of gray and white matter development is similar to that of the rest of the neural tube.
The neocortex (or neopallium) undergoes a second pattern of development to allow for many layers (6)
What role do radial glia have in addition to acting as neural progenitors?
Formation of the Neocortex is......?
Laminar. oldest neurons are deepest
What are the layers of the neocortex?
Layer I—Mostly die (latest to develop)
Layer II--Small and med. pyramidal neurons
LAYERS II and III connected between hemispheres via corpus callosum
Layer III—Small and med. pyramidal neurons
Layer IV—Stellate and granule
MOSTLY RECEIVE SENSORY INFO
Layer V—Large pyramidal neurons
Layer VI (first to develop)
What is the fate of neural crest cells?
•Neural crest forms the majority of the peripheral nervous system
–Adrenal medullary cells
–Tendons of facial musculature
Where are cranial nerves derived from?
neural crest around axis of neural tube.