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Neuroscience > Lecture #2 > Flashcards

Lecture #2 Flashcards

1
Q

what will the cells of the ectoderm form?

A

skin and the CNS

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2
Q

what is the specific subpopulation of cells arising from the anterior region of the developing notochord?

A

Hensen’s node

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3
Q

how could you form an ectopic CNS?

A

transplant the notochord → extremely potent signaling region able to induce the formation of a new and complete CSN

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4
Q

At what time does neurogenesis stop, and the complex process of neuroinduction begin?

A

17 days

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5
Q

what is the most famous signal released by the notochord?

A

Sonic hedgehog (Shh)

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6
Q

what does the neural crest become?

A

central nervous system tube and the epidermis → soon after the closure of the neural tube they start to detach from the nt and ectoderm and start to migrate and spread inside of the developing embryo

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7
Q

what do detached neural crest cells form?

A

contribute to the generation of many tissues and organs

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8
Q

what does it mean if cells are pseudo-stratified?

A

they re attached to the apical and basal membranes, and their nuclei are organized in different levels

their nuclei have particular molarity and they can move up and downside the cytoplasm doing the cell-cycle progression

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9
Q

how does the bending of the tube occur to form the notochord?

A

a certain type of nuclei start to accumulate in a specific position close to the basal membrane and at the same time there is also a force coming from the ectoderm the is pushing the two crests leading to their fusion to create a v-shaped structure and finally a tube

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10
Q

once the tube has formed, what still needs to happen?

A

the anterior neuropore and the posterity neuropore are still open meaning they still have contact with the fluid in the amniotic cavity

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11
Q

what type of mechanism occurs to close the neural tube?

A

the “zip” mechanism

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12
Q

give two reasons why the formation of the notochord is so important:

A
  • it is positioned centrally in the embryo with respect to both the dorsal ventral (DV) and left-right (LR) axis → produces secreted factors signaling to the surrounding tissues providing position and fate information
  • becomes the ossified region forming the vertebrae and contributes to the center of the intervertebral disks
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13
Q

what are neuroectodermal cells?

A

elongated cells that derive from the ectoderm but are converted towards a neural fate by the notochord

differentiate into neurons and microglia (astrocytes and oligodendrocyte progenitors)

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13
Q

what are neuroectodermal cells?

A

elongated cells that derive from the ectoderm but are converted towards a neural fate by the notochord

differentiate into neurons and microglia (astrocytes and oligodendrocyte progenitors)

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14
Q

what are neuroectodermal cells?

A

elongated cells that derive from the ectoderm but are converted towards a neural fate by the notochord

differentiate into neurons and microglia (astrocytes and oligodendrocyte progenitors)

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15
Q

what are the cells called that are located in between the neuroepithelial cells and the ectoderm cells, that detach and start to infiltrate the embryo?

A

neural crest cells (NC)

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16
Q

describe neural crest cells:

A

star-shaped cells that migrate inside of the embryo; some of them undergo the ectoderm to mesoderm conversion

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17
Q

what types of cells can neural crest cells generate?

A
  • melanocytes
  • dorsal root ganglia neurons
  • autonomic ganglia neurons
  • adrenal medulla
  • submucosal nerve plexus of the gut
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18
Q

all bones composing the chest, vertebrae, etc have a mesodermal origin - what is the exception?

A

the skull → derive from neural crest cells and therefore from the ectoderm

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19
Q

what cells do the meninges derive from?

A

neural crest cells and some cells belonging to to the mesenchymal subpopulation

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20
Q

what cells do the meninges derive from?

A

neural crest cells and some cells belonging to to the mesenchymal subpopulation

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21
Q

what are the three layers of the meninges?

A

dura mater, arachnoid, and pia mater

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22
Q

why is the arachnoid complex?

A

there is a trabecula between the arachnoid and the Pia mater the is filled with cerebrospinal fluid

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23
Q

what is the combination of the pia mater and the arachnoid?

A

leptomeninges

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24
Q

what is the function of the meninges?

A

they have a huge number of immune cells that are patrolling the CNS to interact with viruses, bacteria, etc

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25
Q

what is the most famous neural tube defect?

A

spina bifida

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26
Q

what is spina bifida occulta?

A

when there is something wrong with the two neural arches of the vertebrae to where they can’t close, leading to the presence of an empty space between the skin and the two arches

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27
Q

what physical feature is present in some spina bifida babies that allows for diagnosis?

A

the presence of a tuft of hair on the skin in the lumbar-sacral position right above the region of the spina bifida occulta

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28
Q

what is meningocele?

A

a condition where the spinal cord is in the correct position but there is a cyst filled with spinal fluid

29
Q

what is myelomeningocele?

A

a more severe condition in which the spinal cord is not localized in the right position and therefore the system doesn’t work

30
Q

what other condition can coincide with myelomeningocele?

A

Arnold-Chiari malformation: anterior hydrocephalus → the tube circulating cerebralspinal fluid (constantly produced) must be drained, and if not it leads to an accumulation causing the babies not to survive

31
Q

What supplement is able to reduce the incidence of defects by up to 75%?

A

folic acid (400 mg)

32
Q

why is folic acid important?

A

it is a progenitor of DNA protein synthesis and DNA methylation - something can go wrong with cell proliferation

33
Q

what occurs after the closer of the neural tube?

A

the first subdivision → a few hours after the closure we can see the formation of these subdivision: forebrain, midbrain, hindbrain, and long spinal cord

34
Q

what is the term for the forebrain?

A

prosencephalon

35
Q

what is the tern for the midbrain?

A

mesencephalon

36
Q

what is the term for the hindbrain?

A

rhombencephalon

37
Q

what forms from the forebrain?

A

two balloons the are growing anterior laterally in the CNS which are the two telencephalic vesicles: the biggest structures we have in the CNS

Then the formation of the diencephalon

38
Q

what is the diencephalon?

A

a piece of the tube connecting the telencephalon with the posterior regions

39
Q

what two things are generated from the hindbrain?

A

metencephalon and the myelencephalon

40
Q

what is the mesencephalon?

A

a piece of tissue of the CNS connecting the anterior brain to the spinal cord

41
Q

what is formed from the metencephalon?

A

cerebellum: part of the CNS driving movement and coordination

42
Q

how many points of bending are there in the neural tube?

A

three

43
Q

why is the binding of the neural tube important?

A

it allows the embryo to begin to acquire the so called fetal position → midbrain flexure plus the cervical flexure

44
Q

what is the most important part of our CNS?

A

telencephalon vesicle

45
Q

where does the formation of the optical vesicles occur?

A

in the region between the diencephalon and the telencephalon

46
Q

what will the optical vesicles produce?

A

optic stalk, retina, and sensory part of the eye

47
Q

what is the function of the choroid plexa in the telencephalon?

A

they are able to release the cerebrospinal fluids inside the cavity

48
Q

describe the connection of the telencephalon with the two balloons formed:

A

the two telencephalon vesicles are emerging laterally from the tube and they are connected with the diencephalon, and two foramen allow the connection of the cerebrospinal fluid in the tube, but with the cerebrospinal fluid contained in the two tele cephalic vesicles

49
Q

what does the extreme growth of the CNS cause?

A

the invagination of the cerebral cortex forming succi and gyri called gyrihecephalia

49
Q

what does the extreme growth of the CNS cause?

A

the invagination of the cerebral cortex forming succi and gyri called gyrihecephalia

50
Q

why are the folds in the cortex important?

A

initially the surface of the cerebral hemisphere is smooth, but grooves (sulci) and and tortuous convolutions (gyri) allow for a significant increase in surface area

51
Q

describe myeloencephaly and meningoencelphalocele:

A

formation of cysts due to alterations in the closure of the skull causing mental deficiency and retardation

52
Q

what are the two branches of the autonomic nervous system and what are their functions?

A

sympathetic and parasympathetic divisions - not voluntary bur fundamental for the innervation of blood vessels, capillaries, organs, the gut, and the fight or flight response

53
Q

what happens to the nucleus in neuroepithelial cells?

A

it is moving up and down in the cytoplasm

54
Q

where does mitosis always occur?

A

at the boundary between the ventricular cavity and the apical membrane

55
Q

what occurs after the division?

A

the two daughter cells cam inherit filaments connecting the apical and the basal membrane, or sometimes only one of the two cells is connected with he apical and basal membrane while the other enters a new cell fate (differentiation) and this descendant stars to become a young neuroblast and then a neuron

56
Q

describe the tight association with the nuclear position in the cells and cell cycle:

A

the nucleus moves from the CNS wall to the basal membrane and when the nucleus was in the basal membrane, it starts the S phase division, while in G2 division occurred when the nucleus had returned to the apical membrane

then mitosis occurred in a position not far from the apical membrane

57
Q

what is the significance o the inter kinetic nuclear movement?

A

we don’t know - but we know that altering the interkinetic nuclear movement genetically for example can completely destroy the development of the CNS in rodents

58
Q

what occurs during an asymmetrical division?

A

when the spindle is perpendicular to the ventricular cavity → one of the two cells will still be a neuroepithelial cell and able to continue its round of proliferation, but the other will differentiate into neurons

59
Q

what occurs during a symmetrical division?

A

the spindle is parallel to the membrane and the two daughter cells are identical, so they are both neuroepithelial cells that are able to proliferate

60
Q

during development, which type of division is more common?

A

the vast majority of mitosis were parallel oriented suggesting that from this division we had two epithelial cells being able to proliferate again and again so this is why we have a huge tangential expansion

61
Q

what is the hypothesis for the difference in division outcomes?

A

in the apical part of the epithelial cells there is a short piece of submemnrane that contains specific factors and if they two cells are dividing along this plane (perpendicular) then the two daughter cells can inherit the same part of the apical membrane and this means they obtain the same proliferative phenotype

on the other hand, the mitotic spindle which is perpendicular, generates two daughter cells and only one of them can inherit the vertical part of the membrane

62
Q

what are some determinants for the difference in division?

A

notch receptos and many other transmembrane proteins that are often associated with stemness not only in the brain but also in other tissues seem to cluster here in the apical part of the cell and therefore the two cells can inherit the determinants and stay in the epithelial or embryonic cell fate

63
Q

what happens to cells that are dividing with a mitotic plane that is not perpendicular?

A

the other starts to acquire the phenotype of a young neuroblast and soon after the division it enters into contact with the neuroepithelial cell and starts to climb using this connection between the neuroepithelial cells like a rope to move from the germinal region to the post-mitotic region

they are proliferating progenitors but at the same time they are also scaffolds because they allow the descendants that re not stem to use part of their cytoplasm to climb

64
Q

what is the inside out rule?

A

the first neurons generated by asymmetric cell division can cluster just a move the geminal region to form the so called layer 6 of the future cerebral cortex

neurons generated later on can overcome this later and form layer five, and then overcome these two to form layer 4, etc

65
Q

what are these cells called in rodents starting from E10?

A

radial glial cells: radial becyae they re connected to the basal and apical membrane with thin cytoplasmic bundles, and glia because they start to express some markers that are similar to markers expressed by astrocytes

66
Q

what happens when the cells are in position at the cortical plate?

A

they can detach from the rope and differentiate into an adult post-mitotic and functionally active neuron

67
Q

what is this migration mechanism called?

A

early mechanism is called soma translocation

locomotion because the cells are climbing

68
Q

what happens to neuroepithelial cells at the end of neurogenesis?

A

it seems that after the last asymmetric division, the remaining neuroepithelial cells start to detach from the apical membrane, and the retraction of this cytoplasmic bundle allows for the migration of the bodies of these cells from the germinal niche to the cortical plate, and in the cortical plate these cells start to proliferate again, but only for the generation of astrocytes

Neuroscience (19 decks)

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