L2: Neuralation

Question 1

The central nervous system originates as what?

Answer 1

local elongation of ectodermal cells in the dorsal surface of the developing embryonic disc to form a flat sheet, the neural plate.

Question 2

what does the Neural plate give rise too?

Answer 2

part of the autonomic nervous system and somatic motor nerves.

Question 3

At what day does the neural plate develop?

Answer 3

17 – 18 days

Question 4

what happens after the neural plate is formed?

Answer 4

neurulation

Question 5

what is neurulation?

Answer 5

development of a groove in the neural plate, running from rostral to caudal

Question 6

what does rostral to caudal mean?

Answer 6

nose to tail

Question 7

does neuralation vary between different species?

Answer 7

yes

Question 8

what are the walls of the groove formed by neuralation called?

Answer 8

neural folds

Question 9

what position are the neural folds in ?

Answer 9

they curl

Question 10

what produces the shape of the neural folds?

Answer 10

cytoskeletal elements in the cells themselves

Question 11

what happens when neural folds come together?

Answer 11

some neural ectoderm is pinched off and ends up lying on either side of the dorsal edge of the neural tube

Question 12

what is the neural ectoderm that pinched of known as?

Answer 12

neural crest

Question 13

when does the neural crest appear?

Answer 13

appears at about 21 days in humans

Question 14

what does the neural crest give rise too?

Answer 14

the remainder of the peripheral nervous system, the somatic sensory nerves and the rest of the autonomic system.

Question 15

How do the neural folds fuse and what do they form?

Answer 15

The neural folds fuse dorsally turning the groove into a tube.

Question 16

what’s the differentiation of ectoderm dependent on?

Answer 16

the underlying mesoderm

Question 17

what is the formation of the neural plate in the embryo bought about by?

Answer 17

brought about by a process called neural induction

Question 18

The formation of neural plate is triggered by what?

Answer 18

by signals from the mesoderm beneath the plate which also control regional differentiation of the plate.

Question 19

neural induction evidence was found by which scientists?

Answer 19

Spemann and Mangold

Question 20

what did Spemann and Mangold do?

Answer 20

transplanted mesodermal cells from beneath the neural plate of the embryo into an ectodermal region that normally forms epidermis rather than neural plate.

Question 21

In a chick signals of the notochord cause what?

Answer 21

cause the neural plate to bend around medial hinge point.

Question 22

whats the last region to seal in the neural tube formation of a chick?

Answer 22

Typically the posterior neuropores the last region to seal.

Question 23

what doe stem neural tube give rise too?

Answer 23

The neural tube gives rise to the entire CNS.

Question 24

what does the neural crest give rise too?

Answer 24

neural crest will give rise to the PNS.

Question 25

the CNS is derived from the walls of the?

Answer 25

neural tube

Question 26

Initially what is the neural tube composed of?

Answer 26

single layer of rapidly dividing cells which are elongated between the inner and outer surfaces of the tube

Question 27

how thick is the wall of neural tube originally?

Answer 27

1 ell thick, divides to be 3 cells thick

Question 28

whats the inner layer of the neural tube called?

Answer 28

ventricular layer

Question 29

whats the middle layer of the enrol tube called and what is it composed of?

Answer 29

mantle | composed of migrating non-dividing neurones

Question 30

what happen sin the outer most layer of the neural tube?

Answer 30

non-dividing neurones produce growing axons.

Question 31

Neurones which migrate to the anterior of the neural tube may form what?

Answer 31

a presumptive cortical plate which will eventually become cortex

Question 32

somites form what?

Answer 32

33 vertebrae of the vertebral column, the associated voluntary segmental muscles and the dermis

Question 33

whats the somite responsible for?

Answer 33

organising the developing spinal cord and spinal nerves

Question 34

what are the nerves that innervate the skeletal muscle called??

Answer 34

somatic nerves

Question 35

what happens once the neural tube has formed?

Answer 35

the brain begins to differentiate

Question 36

The rostral neural tube swells to form ___ primary vesicles

Answer 36

3

Question 37

what primary vesicles does the rostral neural tube form?

Answer 37

Prosencephalon (telencephalon and diencephalon) Mesencephalon Rhombencephalon

Question 38

when does the swelling of the neural tube take place?

Answer 38

At 3-4 weeks

Question 39

where is the prosencephalon located what does it link too?

Answer 39

nearest to the nose | forebrain

Question 40

mesencephalon means?

Answer 40

midbrain

Question 41

rhombencephalo means?

Answer 41

hind brain

Question 42

The rhombencephalon connects with the rest of the neural tube forming what?

Answer 42

the spinal cord

Question 43

what causes the embryo to bend?

Answer 43

appearance of these three vesicles

Question 44

why does the embryo bend?

Answer 44

by-product of unequal growth in different regions

Question 45

what does the mesencephalic flexure cause?

Answer 45

forms beneath the mesencephalon and causes the head to bend ventrally until the floor of the forebrain lies almost parallel with the floor of the hindbrain.

Question 46

where is the cervical flexure located?

Answer 46

junction of the spinal cord and hindbrain

Question 47

when does the bending increase?

Answer 47

increases between the fifth and the seventh week

Question 48

third bend occurs in the opposite direction in the region of the developing brainstem, whats it called?

Answer 48

pontine flexure

Question 49

The midbrain, or mesencephalon, is connected _______ to the prosencephalon and __________ to the rhombencephalon

Answer 49

anteriorly | posteriorly

Question 50

The 3 chambers will form the ______ and the tissue surrounding them will form what?

Answer 50

ventricles | the forebrain, midbrain, and hindbrain

Question 51

whats flexures?

Answer 51

to bends in the developing brain

Question 52

what causes flexures?

Answer 52

Uneven division of the cells lining the primary vesicles

Question 53

what will the telencephalon give rise too?

Answer 53

the cerebral hemispheres.

Question 54

what does the Diencephalon differentiate in to?

Answer 54

thalamus and hypothalamus

Question 55

what does the thalamus arise from?

Answer 55

the thalamic thickening

Question 56

what happens as the thalamus grows?

Answer 56

As the thalamus grows, it causes the central fluid-filled chamber of the early diencephalon to become squeezed into a slit, forming part of the third ventricle

Question 57

what happens at 24 – 25 days?

Answer 57

the prosencephalon sprouts 2 pairs of secondary vesicles

Question 58

what are the secondary vesicles?

Answer 58

The optic vesicles | The telencephalic vesicles

Question 59

The optic vesicles appear before the telencephalic vesicles , true or false?

Answer 59

true

Question 60

whats the between brain?

Answer 60

diencephalon

Question 61

Telencephalic vesicles grow _____ and ________ then ______ and _______ so that they lie over the diencephalon.

Answer 61

laterally dorsally ventrally posteriorly

Question 62

A further pair of ventricles sprout off the telencephalon to form what?

Answer 62

olfactory bulbs.