5. Development Flashcards

1
Q

which process converts neural plate –> neural tube?

A

neurulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

steps to neurulation

A
  1. lateral edges of neural plate fold DORSALLY
  2. midline neural groove forms
  3. folded edges meet & fuse at midline
    • fusion begins day 22 (cervical region, 5th somite)
  4. neural groove is converted to neural tube
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

which day does neural fusion start?

at which region and somite?

A

fusion begins day 22 (cervical region, 5th somite)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  1. direction of fusion during neurulation
  2. on day 23, neuropores are (closed/open)
A
  1. cranially and caudally
  2. both cranial and caudal neuropores are still open to the amniotic sac
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

which neuropore closes first?

A

*cranial neuropore first (day 25)

and then caudal neuropore (day 28)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

neural crest cells (aka “fourth germ layer”)

  1. from what layer is it formed?
  2. where do they originate?
  3. migration patterns?
A
  1. from ectoderm –> forms neural crest cells
  2. originates from lateral edges of neural plate
  3. migration
  • cephalic region - sheet-like mass migration; pharyngeal arches
  • trunk - chain migration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

neural crest derivatives

A
  • cranial nerve ganglia
  • spinal (dorsal root) ganglia
  • sympathetic chain and pre-aortic ganglia
  • parasympathetic ganglia of GI tract
  • schwann cells
  • glial cells
  • meninges (forebrain)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does the neural tube develop into?

A

CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what do differentiating neuroblasts develop into?

A

these are primitive nerve cells; which these are responsible for neurons.

These migrate and form in mantle layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

layers of the spinal cord

A
  • ventricular
    • develops into neuroepithelium (pseudostratified)
    • differentiates into neuroblasts
  • neuroblasts form mantle layer
    • gray matter
  • marginal layer forms as nerve fibers emerge from neuroblasts
    • white matter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

neuroblasts form mantle layer and develop into…

A

gray matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

marginal layer forms as nerve fibers emerge from neuroblasts and differentiate into…

A

white matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the plates of the spinal cord

A
  • basal plate
  • alar plate
  • roof
  • floor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

basal plate of spinal cord develops into:

A
  • ventral horn w/
  • motor cells

These are primary order sensory cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

alar plate of spinal cord includes, and develops into:

A

second order sensory cells

  • dorsal horn
  • sensory cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

intermediate horn of spinal cord develops into:

A

autonomic nervous system (gray matter)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

central canal develops into

A

cerebrospinal fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

where do the ventral root and dorsal root come from?

A
  • ventral root/ motor nerve fibers arise from cells in basal plate
  • dorsal root/ sensory nerve fibers arise from sensory nerve cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

process of forming dorsal root?

A

(neural crest derivatives –> form outside the spinal cord (dorsal root ganglion) –> processes extend centrally to alar plate, and peripherally to join ventral root –> form sensory nerve cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

axonal growth:

direction and details

A
  1. axons grow towards their target (end) organs
  2. growth cone at apical end of developing axon is guided by molecular signaling
    • towards - chemoattractants,
    • away from- chemorepellants)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

synaptogenesis

A
  • synaptic connection forms when axon interacts w/ target
  • not precise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

apoptosis w/ regards to axonal growth and synaptogenesis?

A

50% of neurons produced during development undergo apoptosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

somites:

precursor; and develops into

A
  1. develop from paraxial mesoderm
  2. differentiate into:
    • sclerotome: the part of each somite in a vertebrate embryo giving rise to bone or other skeletal tissue
    • dermomyotome: the remaining part of the somite left when the sclerotome migrates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

sclerotome: define

A

the part of each somite in a vertebrate embryo giving rise to bone or other skeletal tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

dermamyotome: define

A

the remaining part of the somite left when the sclerotome migrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

purpose of resegmentation of sclerotomes

A
  • resegmentation allows passage of spinal nerves between vertebrae
  • accounts for segmental nerve distribution
    • myotomes - motor innervation
    • dermatomes - sensory innervation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

myotome: define

what does myotome split into?

A
  1. dorsal part of each somite in a vertebrate embryo, giving rise to the skeletal musculature
  2. divides into:
    • epimere: dorsal; deep back muscles
    • hypomere: ventral; develops into hypaxial muscles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

epimere:

develops into

inn. by

A
  1. the dorsal portion of the mesodermal mass in the early development of chordate embryos that gives rise to the skeletal muscles
  2. develops into deep back muscles
  3. inn by dorsal rami
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

hypomere:

develops into

inn. by

A

hypaxial musculature

  • lateral and ventral body wall musculature
  • limb musculature
  • inn by ventral ramus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

3 primary brain vesicles

A
  1. prosencephalon
  2. mesencehalon
  3. rhombencephalon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

which primary brain vesicle develops into:

future forebrain

A

prosencephalon

32
Q

which primary brain vesicle develops into:

future midbrain

A

mesencephalon

33
Q

which primary brain vesicle develops into:

future hindbrain

A

rhombencephalon

34
Q

secondary brain vesicles

(and which primary vesicle they developed from)

A
  1. TELencephalon - prosencephalon
  2. DIencephalon - prosencephalon
  3. MESencephalon - mesencephalon
  4. METencephalon - rhombencephalon
  5. MYELencephalon - rhombencephalon
35
Q

which 2 secondary brain vesicles develop from prosencephalon?

A
  • telencephalon
  • diencephalon
36
Q

which 2 secondary brain vesicles develop from rhombencephalon?

A

metencephalon and myelencephalon

37
Q

brain region at birth from the secondary brain vesicles?

A
  1. telencephalon - cerebrum
  2. diencephalon - diencephalon
  3. mesencephalon - mesencephalon
  4. metencephalon - cerebrum and pons
  5. myelencephalon - medulla oblongata
38
Q

which secondary brain vesicles form the brain stem?

A
  1. mesencephalon (midbrain)
  2. cerebrun and pons
  3. medulla oblongata
39
Q

why can’t we think about the brain stem as a layered ice cream cone?

A

because the cephalic flexure (as a result of cranial/caudal folding) affects the orientation

40
Q

why do we have a cephalic flexure?

A

bc humans assume an upright stance which affects orientation of visual, auditory, and vestibular systems oriented accordingly

curves the axis of rotation

41
Q

forebrain development - end structures

A
  1. telencephalon -
    • future cerebral hemispheres (right and left)
    • cortical structures develop (gyri, sulci, fissures)
  2. diencephalon - assoc. w/ 3rd ventricle
  • eyes +
  • subthalamus
  • epithalamus
  • thalamus (R/L)
  • hypothalamus (R/L)
42
Q

when the telecephalon (R/L hemispheres) growing most rapidly?

A

rapid growth during final 2 months of fetal period

43
Q

diencephalon is assoicated w/ which ventricle?

A

3rd ventricle

44
Q

from which layer does the pituitary gland develop?

A

from ectoderm

  1. starting wk 5, pituitary forms in dorsal midline above thyroid gland
  2. ectodermal pocket in dorsal midline of pharynx
  3. pocket loses connection w/ pharynx –> creating hollow ball of cells inf to floor of diencephalon (posterior to optic chiasm)
  4. cells divide and central chamber disappears –> endocrine mass becomes adenohypophysis
  5. neurohypophysis of pituitary gladn begins as depresion adn grows towards adenohypophysis
45
Q

define the following:

gyri

sulci

fissures

A

gyri: folds

sulci: grooves

fissures: deep sulci

46
Q

cephalic flexure is between which 2 secondary brain vesicles?

A

diencephalon and mesencephalon

changes directional orientation

47
Q

somatotopic organization

A

organized into tracts/ based on region of the body; allows us to determine where the lesion is based on a map like the humunculus

*more complex rostrally

48
Q

pituitary gland develops from which 2 things?

A
  • oral ectoderm
  • diencephalon
49
Q

pharyngeal arches:

made of what?

how many?

covered by what?

A
  1. bars of mesenchyme derived from the mesoderm and neural crest cells
  2. form in 4 pairs around pharynx
  3. covered by ectoderm externally and endoderm internally
50
Q

what is a synonym for branchial?

A

pharyngeal arches

51
Q

difference between pharyngeal pouch vs. cleft?

A

cleft is externally between arches (ectoderm)

pouch is internal between arches (endoderm)

52
Q

which pharyngeal arch tends to disappear betwen 5 weeks and 5 months

A

pharyngeal arch 2 seems to disappear

53
Q

epiglottis forms from which pharyngeal arch?

A

pharyngreal arch 4 (Green)

54
Q

which cranial nerve matches with each arch?

V3 , VII, IX, X

A
55
Q

which cranial nerve is assoc. w/

arch 1

A

trigeminal nerve (V3) mandibular division

56
Q

which cranial nerve is assoc. w/

arch 2

A

facial nerve (CN 7)

-involved in part of taste sensation

57
Q

which cranial nerve is assoc w/

arch 3

A

glossopharyngeal (CN 9)

58
Q

which cranial nerve is assoc w/

ARCH 4 (&6)

A

vagus nerve (CN 10)

59
Q

CC: holoprosencephaly,

and mechanism

A

failure of prosencephalon (& sometimes other bilateral structures) to divide into right and left counterparts;

*injury to anterior midline of germ disc

can cause cyclopia

60
Q

CC: hydrocephalus

(definition, causes, effects)

A
  • build-up of cerebrospinal fluid w/in the brain ventricles –>taking up space in the fixed cavity, compressing other material)
  • causes
    • overproduction of CSF
    • diminished reabsorption of CSF
    • blockage of CSF circulation
  • effects
    • brain damage due to compression of CNS structures
61
Q

CC: neural tube defects

A

spectrum of defects related to incomplete neurulation

62
Q

during which stage of development is body plan refined?

A

gastrulation

(early on in development, we know where cranial and caudal ends are)

63
Q

which CNS congential abnormality results from :

injury to anterior midline of germ disc (due to alcohol or genetics)

A

holoprosencephaly

64
Q

tx for hydrocephalus

A

catheterize the enlarged ventricle –> subcutaneous catheter –> loop of catheter in peritoneum to accomodate growth (diverts to abdominal cavity where it is then absorbed)

65
Q

meninges review: what layers are they and what do they cover?

A
  1. dura (externally)
  2. arachnoid
  3. pia

These cover both the brain and spinal cord

66
Q

CC: anencephaly

A
  • failure of cranial neuropore to close
  • therefore, neural tissue is exposed to amniotic fluid –> necrosis
67
Q

CC: spina bifida

A
  • failure of caudal neuropore to close
68
Q

CC: meningocele vs. meningomyelocele**

A
  • meningocele: protrusion of the meninges through a gap in the spine due to a congenital defect
  • meningomyelocele: *most severe; also CNS structures that have buldged out into the cyst
69
Q

tx to prevent neural tube defects

effects of such tx

A

mandate to fortify cereals w/ folic acid to prevent neural tube defects

the rate of spina bifida has decreased & has now been relatively maintained at lower rate

70
Q

significance of 1st pharyngeal cleft

A

where external auditory meatus forms

71
Q

which is interior?

(pharyngeal pouch or cleft)

A

pharyngeal POUCH

72
Q

which is exterior?

(Pharyngeal pouch or cleft)

A

Pharyngreal CLEFT

73
Q

cc: where is the most common blockage of CSF, leading to hydrocephalus?

A

blockage of the cerebral aqueduct

74
Q

CC: what structure is most likely damaged during hydrocephalus?

why?

A

brain material can be herniated through foramen magnum and damaging CNS (respiratory centers are here)

75
Q

CC: Rachischisis

A

The vertebrae overlying the open portion of the spinal cord do not fully form and remain unfused and open, leaving the spinal cord exposed

Incompatible w/ life