Lecture 23 Flashcards Preview

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Flashcards in Lecture 23 Deck (89):
1

gastrulation is __

the local invagination of a subset of cells in the early embryo

2

gastrulation creates _ germ layers: ___

3; ectoderm, mesoderm, endoderm

3

ectoderm =

nervous system, epidermis

4

mesoderm =

notochord, bone, muscle, connective tissue, gonad

5

endoderm =

GI tract, respiratory tract, endocrine system, auditory system, urinary system

6

the initiation of neural development is critically dependent on what two processes?

gastrulation and neurulation

7

when the process of gastrulation is complete, the embryo will consist of __

3 germ layers (ectoderm, mesoderm, endoderm)

8

an important event in the process of __ is the formation of the notochord

gastrulation

9

the formation of the notochord ___ is very important

at the midline of the gastrulating embryo

10

the notochord is a __ of __ cells, which condense at the __ as ___

cylinder; mesodermal; midline; the mesoderm invaginates

11

the notochord extends from the __ to the __

anterior to posterior

12

during late gastrulation, mesodermal cells in the region of the primitive streak form the __

notochord

13

the notochord is a critical feature - it directs the __ (secretes __)

formation of the nervous system; secretes inductive factors

14

the layer of ectoderm that lies right above the notochord is called the __ which is tiny but gives rise to __

neuroectoderm; the entire nervous system

15

the notochord defines the __ of the embryo; lays out the __ for the entire body

midline of the embryo; symmetry

16

primitive pit is __; which leads to the __, leads to the __

the very first dent; leads to the primitive streak, which leads to the notochord

17

the notochord induces the neuroectoderm to ___

differentiate into precursor cells that thicken and become the neural plate

18

the neural plate is just the __ in another phase/state

neuroectoderm

19

cells from the __ and the __ send chemical/molecular signals to the neuroectoderm, which causes a subset of cells to __.....this process intiates __

notochord and primitive streak; differentiate into neural plate precursor cells; neurulation

20

the thickening is called the __

neural plate

21

the lateral margins of the neural plate begin to __, which transforms the plate into a __

fold upward; tube

22

the cells within the neural tube give rise to __

the brain and spinal cord

23

those neuroectoderm precursor cells are the __. they are __ and have the capacity to __

progenitors of the neural tube; stem cells; give rise to any cell class found in the mature nervous system

24

neural crest cells are at the border of the __ and the __

neural plate and the non-neural ectoderm

25

neural crest cells are a __ group of cells and are unique to __

temporary; vertebrates

26

3 examples of what neural crest cells give rise to

cartilage, bone, smooth muscles

27

what are the "neural stem cells"?

the neuroectodermal precursor cells

28

how are neural stem cells different than embryonic stem cells?

they cannot give rise to ANYTHING, it has to be some neural tissue

29

neural stem cells divide to produce __

more precursor cells

30

neural stem cells give rise to __

neurons, astrocytes, oligodendrocytes, glia, etc.

31

what do neural stem cells depend on to determine what they become?

the local environment (molecular cues)

32

the neural tube also contains specialized epithelial-like cells called the __

floorplate

33

the floorplate secretes molecular signals that __

specify position and fate of neural progenitors

34

are all cells in the neural tube self-renewing?

no

35

neural tube also gives rise to a subset of progenitor cells called the __

neural crest

36

floorplate gives rise to __

hindbrain and spinal cord

37

the neural crest differentiates into __

neurons and glia of the sensory and visceral motor ganglia, neurosecretory cells of the adrenal gland, and neurons of the enteric nervous system

38

differentiation is dependent on __

the type of environment they end up in

39

neural crest cells migrate and move along __

four distinct pathways

40

4 pathways of neural crest cells

sensory, autonomic ganglia, adrenal neurosecretory cells, and melanocytes/non-neuronal cells

41

cell signaling during migration influences __

progenitor identity and terminal differentiation

42

soon after the neural tube forms, the ___

fore-runners of the major brain regions start to become more apparent

43

soon after the neural tube forms, __ begins to shape the neural tube into different regions

morphogenesis

44

primitive brain regions (4)

prosencephalon, mesencephalon, rhombencephalon, and spinal cord

45

the first bend (towards the head) is called the __, which gives rise to the ___, which gives rise to the __

cephalic fixture; prosencephalon; forebrain

46

the second bend (towards the tail) is called the __

cervical flexure

47

the mesencephalon gives rise to the __

midbrain

48

the rhombencephalon gives rise to the __

hindbrain

49

neural tube forms a precursor to the __

spinal cord

50

lateral aspects of the prosencephalon form the __, which gives rise to __ (4)

telencephalon; cerebral cortices, hippocampus, basal ganglia, and forebrain nuclei

51

caudal aspects of the prosencephalon form the __, which gives rise to __ (3)

diencephalon; thalamus, hypothalamus, and optic vesicles/cups (eventually forming the retina)

52

dorsal portion of the mesencephalon forms the __

superior and inferior colliculi

53

ventral portion of the mesencephalon gives rise to the __

tegmentum

54

rostral portion of the rhombencephalon forms the __ which gives rise to the __ (2)

metencephalon; cerebellum and pons

55

caudal portion of the rhombencephalon forms the __ which becomes the __

myelincephalon; medulla

56

how can this simple tube beget such a variety of brain structures?

genes

57

the neural tube is organized into repeating units called __

neuromeres

58

the segmentation establishes __

regional identity

59

4 examples of homeobox genes

bcd, kr, h, wg (wingless)

60

expression patterns of genes (___) guides the differentiation of the embryo into __ that gives rise to different regions of the body

homeobox genes; distinct segments

61

homeobox genes are __ that direct the expression of other genes that mediate __

transcription factors; morphogenesis

62

vertebrates also have __ which are expressed only in the __ (2)

hox genes; posterior hindbrain and spinal cord

63

hox gene expression coincides with the __

formation of morphological features

64

neural stem cells are __ cells that can give rise to __

multipotent; many different neuronal cell types

65

neural stem cells must acquire __

instructions to terminally differentiate into the appropriate cell type

66

when you transfer neuronal stem cells to a new region they can __ (2)

acquire the identity of that new region; retain an identity that reflects their origin

67

when you remove neural stem cells, (3)

compensated by local proliferation; causes little change; disrupts development

68

it is the __ that is essential for regional identity

interactions between cells

69

neural induction =

just the instructions that tell a neural stem cell what to become

70

genes are expressed in different areas of the neural tube

.

71

local signaling molecules =

molecules that play a role in morphogenesis and/or neuronal differentiation

72

sonic hedgehog is expressed and secreted by the __ (2)

notochord and floorplate

73

sonic hedgehog is important for (2)

closing the neural tube; establishing the identity of neurons in the ventral portion of the spinal cord and hindbrain

74

mutations of sonic hedgehog result in __

failed division

75

when sonic hedgehog is present it binds to __ and ___, this causes disassembly of __ which goes on to affect genes

patch; __ ; protein GRI1

76

BMP =

bone morphogenetic proteins

77

the BMPs expressed in the __ promote __, and also turn ___ into __

mesoderm; osteogenesis; ectodermal cells; skin

78

Noggin and chordin sequester BMP, preventing the __ cells from becoming __ and they instead form __

neuroendodermal cells; epidermis; neuronal tissues

79

noggin and chordin are __ that modulate signaling via __

endogenous antagonists; TGF-beta family

80

morphogenic factors exist in __

gradients

81

the identity of motor and interneurons in the ventral vs dorsal spinal cord reflects the __

graded local signals of Shh, noggin, and other morphogens

82

neurogenesis begins after __ is complete

initial patterning of the neural tube

83

precursor cells have the __ that assign basic identities

signature gene expressions

84

precursors are at the __ and differentiate there

ventricular zone

85

precursors form __ or __

new neuronal stem cells or postmitotic neuroblasts

86

precursor cells in the neural epithelium are attached at the __ and the _

ventricular surface and the __ surface

87

during neurogenesis, the __ move, when the cell is closest to the __ surface of the neural tube it will undergo __

nucleus of the cells; outer (plial); DNA synthesis

88

neuronal production and migration: symmetrical division yields __

2 identical progenitor cells

89

neuronal production and migration: asymmetrical division yields __

1 progenitor cell and 1 neuroblast