Neurulation Flashcards

1
Q

Week 4

A

Neurulation

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

Steps of neurulation

A

1.) Neuroectodermal tissues differentiate from the ectoderm and thicken into the neural plate; the neural plate border separates the ectoderm from the neural plate

2.) The neural plate bends dorsally, with the two ends eventually joining at the neural plate borders, which are now referred to as the neural crest

3.) The closure of the neural tube disconnects the neural crest from the epidermis; neural crest cells differentiate to form most of the peripheral nervous system

4.) The notochord degenerates and only persists as the nucleus pulposus of the intervertebral discs; other mesoderm cells differentiate into the somites, the precursors of the axial skeleton and skeletal muscle

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

Neurulation highlights

A
  • notochord induces overlying ectoderm to develop into the neural plate
  • the neural plate folds into the neural tube and the neural crests are pinched off
  • the neural tube derives the CNS
  • the neural crests derive the PNS and select other cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

During gastrula (week 3 development), the body axis is formed

A
  • bilateral symmetry
  • left and right
  • dorsal and ventral
  • cranial and caudal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Week 3

A
  • triploblastic/trilaminar disc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What germ layers are formed during gastrulation?

A
  • ectoderm
  • mesoderm
  • endoderm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Notochord

A

Sonic Hedge Hog (SHH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The mesoderm differentiates into how many types?

A

3

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

Primitive streak becomes

A

primitive groove

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

Primitive node becomes

A

primitive pit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The notochord secretes SHH, which dictates what?

A

cellular involvement

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

Neural plate

A
  • neural groove
  • neural folds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

During neurulation, the neuroectodermal cells transform into what?

A

neural tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Neural tube becomes what?

A

brain and spinal cord

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

The neural tube activates what?

A
  • neural crest cells
  • further differentiation of ectoderm, mesoderm, and endoderm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Central Nervous System (CNS)

A
  • brain
  • brain stem
  • spinal cord
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Peripheral Nervous System (PNS)

A
  • cranial nerves
  • peripheral body nerves
  • ganglion
  • sensory and motor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Steps at ectoderm: primitive area makes

A

primitive streak –> groove
primitive node –> pit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Primitive node

A

“Hensen’s node” or “Spemann-Mangold Organizer”
- notochord and SHH and axial mesoderm

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

Notochord and SHH and Axial mesoderm stimulates what?

A

Neural plate (replaces primitive streak at day 25)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Neural plate makes

A
  • neural groove
  • neural folds

which makes the neural tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Steps at ectoderm: Cells at primitive NODE (let’s make a tube)

A
  • they direct organization
  • cells that DIVE through groove and travel CRANIALLY become the prechordal plate and notochord (which stimulate neurulation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Steps at ectoderm: Cells at primitive NODE

Ectoderm: neural plate –> _______ ____

Ectoderm: surrounding plate –> ______

A

neural tube; epidermis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

At primitive NODE, what happens to the cells at the cranial end?

A

they proliferate

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

At the primitive NODE, once plate is formed it undergoes __________ by _______ _______

A

elongation; convert extension

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

Neural plate

A

communication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How do germ cells communicate at the neural plate?

A

induction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

At the neural plate, mesoderm causes overlaying ectoderm to undergo molecular and cellular changes

A

1.) Cells proliferate (increase mitosis)
2.) Cells express new sets of mRNA’s specific for neural development “markers” including CAM’s (cell adhesion molecules)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

If cells transplant incorrectly—

A

two-headed organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Neural plate – communication – cell movement

A

cells undergo shape and behavioral changes
- columnarization
- apical constriction
- convergent extension
- cell crawling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Neural plate –> hinge and close –> neural tube

A

1.) The sheet bends at a median hinge joint, creating neural folds
2.) The sheet bends further at lateral hinge joints, closing at the top to form the neural tube
3.) Neural crest cells detach from the epithelial tube and become wandering mesenchyme cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Neural crest cells “4th germ layer”

A
  • specialized cells within neural tube
  • migrate outward through the fetus
  • give rise to NEW tissues
33
Q

Neural crest cells make up the sensory epithelium of what?

A
  • ears
  • nose
  • eyes
  • mouth
34
Q

Neural crest cells make up what glands?

A
  • sweat
  • mammary
  • pituitary
35
Q

Movement of cells for neurulation in dorsal view

A
  • neural tube is OPEN
  • “pores” close –> neural tube is CLOSED
  • Neural tube is NOW formed
36
Q

Day 18-Day 23

A
  • Cranial (anterior) neuropore
  • Caudal (posterior) neuropore
37
Q

Otic placode

A
  • otic vesicles
  • cochlea
  • inner ear
38
Q

Surface ectoderm

A
  • nose
  • mouth
  • epidermis of fetal skin
  • hair
  • nails
  • sweat glands
  • mammary glands
39
Q

Where are the somites found?

A

Under ectoderm

40
Q

Lens placode

A
  • lens
  • cornea
41
Q

Steps at mesoderm: notochord

A
  • secretes SHH protein
  • tells the cells where they are in 3D space
  • SHH permeates embryo
  • day 20: differentiation of 3 mesoderm types
42
Q

3 mesoderm types

A

1.) Paraxial mesoderm
2.) Intermediate mesoderm
3.) Lateral mesoderm

43
Q

The paraxial mesoderm becomes _________

A

Somites

44
Q

Somites

A

PAIRED blocks of mesoderm, closest to Notochord

45
Q

Paraxial mesoderm (somites)

A
  • paired
  • formed alongside NOTOCHORD
  • cranial to caudal development
  • 3 somites per day are formed
  • can dictate how old embryo is
46
Q

How many somites are formed each day?

A

3

47
Q

Paraxial mesoderm Somites give rise to what 3 groups of mesodermal tissues?

A

1.) Dermatome (skin)
2.) Myotome (muscle)
3.) Sclerotome (hard)

48
Q

Sclerotome

A
  • bones
  • cartilage
49
Q

Intermediate mesoderm

A
  • smaller
  • lateral to somites

ex. adrenal cortex, kidneys, testes and ovaries

50
Q

Lateral mesoderm

A
  • thinnest
  • most lateral
51
Q

Lateral mesoderm splits into which two layers at week 3?

A

1.) Dorsal portion: Somatic/Parietal
2.) Ventral portion: Splanchnic/Visceral

52
Q

Somatic/parietal (dorsal) mesoderm

A

Adheres to ectoderm
- parietal pleura; soft tissue of arms and legs

53
Q

Splanchnic/visceral (ventral) mesoderm

A

Adheres to endoderm
- visceral pleura; muscle wall of gut, heart, circulatory system

54
Q

Space between the 2 mesoderm layers is called what?

A

Intraembryonic coelom

55
Q

Intraembryonic coelom is a space that houses what?

A

Thoracic and abdominal cavities

56
Q

Paraxial mesoderm (somites) forms

A
  • skin
  • muscle
  • bony tissue
57
Q

Intermediate mesoderm forms

A
  • adrenal glands
  • gonads
  • kidneys
58
Q

Lateral mesoderm forms

A
  • serous membrane
  • limb tissue
  • heart
  • circulatory system
59
Q

Steps at Endoderm: Endo and Ecto push together to form 2 bilaminar regions called?

A

1.) Oropharyngeal membrane or buccopharyngeal (head)
2.) Cloacal membrane (rear)

60
Q

Week 4

A

opening mouth

60
Q

Week 7

A

opening anus and genitourinary tracts

61
Q

Steps at Endoderm: week 4 Embryo folds in which 2 directions along LONGITUDINAL plane?

A

1.) Cranial fold
2.) Caudal fold

62
Q

Movement of cells at the endoderm take on a _______ curved appearance, which helps to form ____ _____ and yolk area at middle

A

“shrimp”; gut tube

63
Q

Steps at Endoderm: Mesoderm follows the endoderm to form ____ layer of that structure

A

2nd
- ex. blood vessels

64
Q

Steps at Endoderm: The two sides of the body will come together at ventral surface and eventually ____, but the yolk sac is in the ___

A

fuse; way

65
Q

Steps at Endoderm: The gut is divided into which 3 regions?

A
  • foregut
  • midgut
  • hindgut
66
Q

Foregut

A

at week 4: mouth opening connects others

at week 5: trachea and lungs

67
Q

Midgut

A
  • stays connected to yolk sac through yolk stalk or vitelline duct
  • stalk thins over time and collapses
  • yolk sac dissipates
68
Q

What is a remnant of yolk stalk called in the midgut?

A

Meckel’s Diverticulum

69
Q

Hindgut

A
  • at week 7: anus opening connects anal canals at pectinate line (large intestine/anus junction)
70
Q

Hindgut feature that connects anal canals

A

pectinate line

71
Q

Endoderm forms the linings of the gastrointestinal tube and respiratory tube…

A
  • tonsils
  • thyroid
  • parathyroid glands
  • thymus
  • liver
  • gallbladder
  • pancreas
  • parts of ear
  • epithelium of urethra and urinary bladder
  • GI tract and pharynx
  • respiratory tract
72
Q

Pharynx

A

pectinate line (GI tract endoderm)

73
Q

Primitive streak and node becomes what?

A

neural tube

74
Q

Notochord

A
  • Transient contributes to nucleus pulposus
  • influences embryo folding
  • secretes Sonic Hedge Hog
75
Q

Steps of neurulation

A

1.) Neural plate (3 types of mesoderm)
2.) Neural groove
3.) Neural folding
4.) Neural tube

  • 3 pairs a day
  • by week 5, 42-44 pairs
76
Q

Intermediate mesoderm

A
  • kidneys
  • adrenal glands
  • urogenital system
77
Q

Lateral plate mesoderm

A
  • heart
  • blood vessels
  • organ muscle
  • body wall