development of the CNS

Question 1

what are the stages the CNS development?

Answer 1

neurulation
neural proliferation
neural migration
apoptosis
synaptogenesis
myelination

Question 2

what is gastrulation?

Answer 2

single-layered blastula reorganizes into a multi-layered structure called the gastrula, which forms the basis for the development of the three primary germ layers of the embryo: the ectoderm, mesoderm, and endoderm

Question 3

when does gastrulation begin?

Answer 3

3 weeks of pregnancy

Question 4

what process creates the 3 germ layers?

Answer 4

involution- cells of surface of embryo fold inwards

Question 5

what is the ectoderm?

Answer 5

cells that remain on the outer surface of the embryo form the ectoderm, which will give rise to the skin, nervous system (including the brain and spinal cord), and sensory organs

Question 6

what is the mesoderm?

Answer 6

cells that move inward between the ectoderm and endoderm form the mesoderm, which will become muscles, bones, the circulatory system, kidneys, and other internal structures

Question 7

what is the endoderm?

Answer 7

cells that move deepest into the embryo form the endoderm, which will become the lining of the digestive and respiratory systems, including organs like the liver, pancreas, and lungs

Question 8

what is neurulation?

Answer 8

process during early embryonic development in which the neural tube is formed from the neural plate

Question 9

when does neurulation occur?

Answer 9

3-4th week of gestation

Question 10

stages of neurulation

Answer 10

1. formation of neural plate
2. shaping of neural plate
3. formation of neural tube
4. closure of neural tube
5. formation of neural crest

Question 11

neural plate formation

Answer 11

after gastrulation, the ectoderm forms the neural plate
the neural plate is a thickened region of ectoderm that appears on the midline of the dorsal embryo

Question 12

shaping of neural plate

Answer 12

neural plate begins to fold at its lateral edges, which gradually move toward each other=neural folding
the central region of the neural plate forms a groove called the neural groove

Question 13

neural tube formation

Answer 13

neural folds continue to move closer to each other, eventually fusing at the midline
this fusion process forms the neural tube, a hollow structure that will give rise to the brain and spinal cord.
the anterior (cephalic) part of the neural tube will become the brain
the posterior part will form the spinal cord

Question 14

closure of neural tube

Answer 14

begins in the middle of the embryo and proceeds anteriorly and posteriorly
completed at 4th week of development

Question 15

neural crest formation

Answer 15

neural crest is made by the folds of the edges of the neural tube
neural crest cells migrate away from the neural tube and give rise to a wide variety of structures, including sensory neurons, ganglia, schwann cells and parts of the skull (PNS)

Question 16

what are the two most common NTD (neural tube defects)?

Answer 16

anencephaly and spina fibida

Question 17

what is anencephaly?

Answer 17

anterior part of the neural tube fails to close resulting in the absence or undevelopment of major parts of the brain
closure of the anterior neuropure occurs at around day 25-28
those born with anencephaly die very quickly or are stillborn

Question 18

what is spina bifida?

Answer 18

posterior part of neural tube fails to close resulting in the incomplete development of the spinal cord and the vertebral column
posterior neuropore closes at around day 27

Question 19

what are the types of spina bifida?

Answer 19

spina bifida occulta
spina bifida cystica (meningocele and myelomeningocele)

Question 20

what is spina bifida occulta?

Answer 20

mild form where vertebrae are deformed but cord and nerves are unaffected

Question 21

what is meningocele?

Answer 21

severe form in which meninges bulge out through vertebrae but spinal cord stays in place

Question 22

myelomeningocele

Answer 22

most severe form where spinal cord and meninges protured through opening in the vertebrae

Question 23

how to prevent NTDs?

Answer 23

folic acid supplementation (synthetic form of folate)
supplementation at least one month before conception and during the first trimester of pregnancy

Question 24

what are the three primary brain vesicles?

Answer 24

prosencephalon, mesencephalon and rhombencephalon

Question 25

when do the vesicles begin to develop?

Answer 25

following the development of the neural tube (4th week)

Question 26

when does the prosencephalon divide into the telencephalon and the diencephalon?

Answer 26

week 5

Question 27

when do the telencephalon and diencephalon diffrentiate?

Answer 27

week 6 and beyond

Question 28

when does the rhombencephalon divide into the myelencephalon and metencephalon?

Answer 28

4-5 weeks

Question 29

when does the myelencephalon develop the medulla?

Answer 29

5-7 weeks

Question 30

what plates form the dorsal and ventral parts of the spinal cord?

Answer 30

alar plate forms the dorsal
basal plate forms the ventral
at around 4-6 weeks

Question 31

what layers are the grey and white matter formed by?

Answer 31

mantle layer forms grey
marginal layer forms the white
at 6-10 weeks

Question 32

when do spinal nerves and ganglia form?

Answer 32

6-12 weeks

Question 33

what condition impacts formation of neural crest?

Answer 33

foetal alcohol syndrome

Question 34

how does FAS affect the neural crest?

Answer 34

neural crest cells are highly migratory and alcohol interferes with the signals that guide migration
e.g Wnt Notch and Sonic Hedgehog (Shh) pathways
can also induce oxidative stress which leads to apoptosis of neural crest cells
disrupts cell proliferation adn progenitor cells which generate neurons and glial cells