Neural Development Exam 1

Front 1

Cleavage and Blastocyte formation

Back 1

Oocyte- zygote- 4 cell- 8 cell- morula (16 cell)- blastula

Front 2

Blastocyte

Back 2

Inner Cell Mass
~ hypoblast (outer)
~ epiblast (inner)
Blastocoel
Trophoblast

Front 3

Epiblast

Back 3

becomes amniotic sac

Front 4

Hypoblast

Back 4

becomes yolk

Front 5

Gastrulation

Back 5

2 layers of embryo become 3
1)primitive streak forms in amniotic sac- axis of embryo, dorsal/ventral, anterior/posterior
2) epiblast cells migrate to primitive streak & displace hypoblast
3) Primary germ layers formed by epiblast cells
- 1 endoderm
-2 mesoderm
-3 ectoderm
4) notochord formed out of mesoderm cells just below primitive streak

Front 6

Neurulation

Back 6

ectoderm to neural tissue
1) Thickening of neural tissue-- neural plate
2) Neural groove/ neural folds formed on either side
3) Neural folds--neural crest
4) Neural tube is formed --ventricles brain spine
5) Neural crest cells-- PNS
Notochord sits below neural tissue and "tells" it to thicken

Front 7

Formation of brain vesicles

Back 7

1) Neural tube formed- allows for cell division& formation
2)Prosencephalon-- forebrain
Mesencephalon-- midbrain
Rhombencepalon-- hindbrain
3) Then...
Forebrain-- telencephalon/ diencephalon
Midbrain-- mesencephalon
Hindbrain-- metencepalon/ myelencephalon

Front 8

Production of brain cells

Back 8

Initially in lining of neural tube, in ventricular zone
3 layers form-- ependymal, mantel, marginal

Front 9

Stem Cells

Back 9

come from blastocyte stage
multipolar-- either glial or neural
Glial-- become asterocytes or oligodendrocytes
Neural-- become neurons

Front 10

Secondary Cell Birth Area

Back 10

cerebellum-- after fully grown, stops
hippocampus/ olfactory cells-- form new cells
subventricular zone

Front 11

Neuronal Migration

Back 11

new neurons travel down radial glial cells
use chemical stim
tissue layers form inside out

Front 12

Neuronal Maturation

Back 12

1) Dendritic arborization
2) Axon Extension
~Filopodia on Growth Cone
~ F-actin allows them to move
3) Axon guidance
~growth cone reaches to target cell through concentration gradient (high-low)

Front 13

Synaptogenesis

Back 13

growth cone follows chemical released by target cells

Front 14

Synaptic Pruning

Back 14

More synaptic connections are created than needed
~ based on experiences, some stay, some go

Front 15

Myelination

Back 15

1) occurs last, especially in frontal cortex
2) oligodendrocytes send out processes to axon, and wrap themselves around
~~ spaces called nodes

Front 16

Formation of Neural Plate

Back 16

*look at previous slides up to gatrulation
1) primitive pit (aka primitive node, organizer, spemenn's organizer, hensens node)

Front 17

Mesoderm formation

Back 17

the notochord also forms
--the cells above the notochord, are told to become the neurveous system

Front 18

From Notochord

Back 18

chemical signals are released
then fade
this allows the ectoderm on top to form the nerve cord

Front 19

Search for Neural Inducers

Back 19

1924-1993
embryo treated with lithium-- hyperdorsolized embryo occurs
embryo treated with UV rays-- no NS
Took UV embryo and treated it with mRNA from lithium embryo-- created rescued NS

Front 20

Primitive Pit Example

Back 20

in frogs
took 1 blastopore from one frog and put it on host blastula-- formed 2 complete NS
implies, organizing signal that tells cells passing through primitive node to become the NS

Front 21

Neural Inducers

Back 21

Bone Morphogenic Protein 4
(Bmp4)
--induces epidermal gene expression
--released by mesoderm as a whole

Front 22

Noggin/ Chordin

Back 22

secreted by notochord
block Bmp4 to inhibit binding wich induces neural tissue to form
LOOK AT PICTURE
no matter where notochord is placed, neurvous tissue will occur

Front 23

Establishment of Spatial Axes
Dorsal/Ventral Patterning

Back 23

Gradient of Sonic Hedgehog (Shh)
Gradient of Bmp4 antagonist

Front 24

Establishment of Spatial Axes
Right/ Left Patterning

Back 24

Cilia in Node establish right and left flow
-Morphogen has high concentration on right side
Gene expression differs on right & left
--Snail-- Right
--PitX2-- Left

Front 25

Establishment of Spatial Axes
Anterior/ Posterior Patterning

Back 25

Noggin/ Chordin-- anterior
Wnt-- posterior

Front 26

Spemann's Experiment with Spatial Patterning

Back 26

early signal produces 2 brains
late signal produces 2 posterior ends
SO
embryos are first exposed to anterior signal (Noggin/Chordin)
later exposed to posterior signal (Wnt)

Front 27

Stem-Cells

Back 27

Do divide indefinitely in body-- outside body, they act strange and die
-self-renewel
-totipotent
-pluripotent
~can become any somatic cell
~have both X chromosomes active still

Front 28

Embryonic Stem-Cells (ESC's)

Back 28

created by inner cell mass of blastocyst-- become pluripotent stem cell
--can be neural, cardiac muscle, or blood cell

Front 29

Epiblast Stem Cells

Back 29

have already undergone X chromosome inactivation

Front 30

Embrionic Germ Cells

Back 30

either egg or sperm

Front 31

Adult (somatic) Stem Cells

Back 31

in bone marrow
in skin
in brain (hipp, sub-ventricular, olfactory)

Front 32

Shape and Change

Back 32

Neural plate elongates due to change in shape of cells

Front 33

Folding = primary neurulation

Back 33

Medial hinge points form (neural groove and fold)
Dorsolateral hinge points form

Front 34

Convergence and Closure

Back 34

Requires cell adhesion molecules (NCAM) and cell recognition molecules
Closures in 2 directions form cranial and caudal neuropores

Front 35

Dorsal-Ventral Patterning
(Hind and Spine)

Back 35

at this point, the neural tube as fairly undifferentiated cells
~Dorsal-- roof plate
~Ventral-- floor plate
-- roof, sensory neurons
-- floor, motor neurons
sulcus laminus lines inside
Wnt

Front 36

Notochord

Back 36

located below floor plate
-- if removed, no floor plate, ONLY dorsal structures
-- if transplanted, enduce ectopic motor neurons
Notochord Shh---- clearly, Shh involved in ventral structures

Front 37

Dorsal Structures

Back 37

induced by Bmp4 and Bmp7
~expressed by epidermal cells

Front 38

Ventral Structures

Back 38

Shh expressed in notochord THEN floor plate

Front 39

Dorsal-Ventral--> Anterior Region

Back 39

median-ganglionic eminence
lateral-ganglionic eminence
caudal-ganglionic eminence
~ all 3 large grouping of cells that then migrate

Front 40

Ventral structures

Back 40

induced by Shh
~ expressed by mesoderm

Front 41

Dorsal Structures

Back 41

induced by Gli3
Dorsal--sensory cortex

Front 42

Anterior-Posterior Specification

Back 42

formation of Rhombomers

Front 43

Rhombomer

Back 43

collection of cells
8
all cells within 1 rhombomer wil serve a specific function together
segmented pattern determined by HOX gene

Front 44

HOX gene

Back 44

found in fruit fly
absolute segmentation in HOX (direct segementing)
Cerebellum arises from Rhombomers

Front 45

Retinoic Acid

Back 45

contributes to anterior posterior patterning
High concentration posterior
degraded in anterior
secreted by paraxial mesoderm
Influences HOX gene expression by gradient or timing
derivitive of Vit A

Front 46

Isthmus

Back 46

boundry between tectum and cerebellum

Front 47

Prosomeric Model of Forebrain Development

Back 47

Not as organized as Rhombomer

Front 48

Early Patterning of cerebral cortex

Back 48

established by differential expression of Emx2 and Pax6
~these inhibit one another to promote specification

Front 49

Emx2

Back 49

Large motor
Shrunk visual

Front 50

Pax6

Back 50

Large visual
Shrunk motor

Front 51

Bmp4

Back 51

Dorsal/Ventral
Before neural tube closure-- Induces Ventral structures
After neural tube closre--
Induces dorsal sturctures

Front 52

Noggin/ Chordin/ Fillostatin

Back 52

Anterior/Posterior
Inhibits Bmp4
Promotes anterior structures

Front 53

Wnt

Back 53

Anterior/Posterior
Induces anterior structures
e.g. hindbrain/ spinal cord

Front 54

Shh

Back 54

Dorsal/Ventral
Induces Ventral structures

Front 55

Hox

Back 55

Gene expressing trans. factor
induces neurons in Rhonbomere sequence

Front 56

RA

Back 56

Anterior/Posterior
Ritonoic Acid
derivitive of Vit. A
induces posterior structures

Front 57

Emx2

Back 57

Anterior/Posterior
Induces Posterior sturctures
e.g. visual cortex

Front 58

Pax2

Back 58

Anterior/Posterior
Induces Anterior structures
e.g. motor cortex