Final exam Flashcards
(298 cards)
1
Q
Ectodermal derivatives
A
Surface ectoderm
Neural crest
Neural tube
2
Q
What does surface ectoderm become
A
Epidermis
Hair
Mouth epithelium, tooth, enamel
Lens, cornea
3
Q
What does the neural crest become
A
- peripheral nervous system
- neurons
- glia
- melanocytes
- facial cartilage
4
Q
What does the neural tube become
A
- Brain
- spinal cord
- retina
5
Q
Establishment of neural cells
A
Multipotent cells –> competance –> specification –> commitment –> differentiation –> neuroblasts
6
Q
Neural plate formation
A
Neuroectoderm induced by pharangeal endoderm and dorsal mesoderm
7
Q
Neural tube formation
A
Plate pushes on sides to form folds. Folds push to form neural tube
8
Q
Neurulation
A
Neural tube formation
9
Q
Anterior neural tube
A
Brain
10
Q
Posterior neural tube
A
Spinal cord
11
Q
What undergoes neurulation first
A
Anterior. Posterior is still undergoing gastrulation during this
12
Q
Where does primary neurulation occur
A
Anterior
13
Q
Where does secondary neurulation occur
A
Posterior
14
Q
What do midline ectodermal cells become during neural plate formation
A
Columnar
15
Q
What induces midline ectodermal cells to become columnar during neural plate formation
A
Dorsal mesoderm and pharangyal endoderm
16
Q
What induces medial hingepoint cells
A
Notochord
17
Q
What are medial hingepoint cells anchored to
A
Notochord
18
Q
What happens to the shape of hingepoint cells
A
Decrease in height, form wedge shape (cytoskeletal changes)
19
Q
How does primary neurulation take place
A
Surface ectoderm (epidermis) pushes folds together
Paired folds adhere and merge
Neural crest cells migrate individually
20
Q
What type of hinge points in primary neurulation
A
Dorsolateral hinge points (DLHP)
21
Q
What are DLHP anchored to
A
Surface ectoderm
22
Q
What happens to the shape of DLHP
A
Decrease in height, become wedge shaped
23
Q
What purpose do hinge points serve
A
Neural tube pivots around hinge points
24
Q
What happens within the cord in secondary neurulation
A
Cavitation within the cord
25
True or false, neural tube closure is simulataneous throughout the tube
False
26
How many closure initiation sites in mammals
3
27
How many open ends in mammals
2
28
Open ends in mammals
Anterior neuropore and posterior neuropore
29
Failure to close posterior neuropore
Spina bifida
30
Failure to close anterior neuropore
Anencephaly
31
Failure of the entire neural tube to close over the entire body axis
Cranioarchischisis
32
What causes neural tube defects
Complex genetic and environmental factors
33
What must neural tube cells do to prevent defects
Adhere to eachother, move as a tissue, separate from neural crest and epidermis
34
Genes responsibe for neural tube
Pax 3, sonic heddgehog, openbrain
35
Environmental factors that contribute to neural tube
Folic acid, low socioeconomic groups, seasonal variation, fungal contmination
36
Levels of neural tube differentiation
1. Gross anatomical
2. Tissue
3. Cellular
37
1. Gross anatomical
Neural tube and its lumen bulge and constrict to form the chambers of the brain and spinal cord
38
2. Tissue
Cell populations within the neural tube wall rearrange themselves to form different functional regions of the brain and spinal cord
39
3. Cellular
Neuroepithelial cells differentiate into numerous types of nerve cells (neurons) and supportive cells (glia)
40
How many primary vesicles in the early brain
3
41
How many secondary vesicles in the late brain
5
42
Another name for the forebrain
Prosencephalon
43
Another name for the midbrain
Mesencephalon
44
Another name for the hindbrain
Rhombencephalon
45
What causes inflation of the neural tube
Osmotic pressure from Na+/K+ATPase activity and production of CSF
46
Where is dye before occlusion
Stays in ventricles
47
What happens to the hollow cavity after occlusion
It disappears
48
Where does dye go after occlusion
Everywhere because tissue is reopened
49
How is the neural tube dorsalized
On the dorsal ventral axis
50
What induces dorsal ventral polarity
Signals from the immediate environment
51
What does the ventral pattern of the neural tube come from
Notochord
52
What does the dorsal pattern of the neural tube come from
Overlying epidermis
53
What sends info left and right and up and down to and from the brain
Interneurons
54
Where does sensory information enter on the neural tube
Posterior, dorsal
55
Where does motor information come out from on the neural tube
Ventral side
56
What side of the neural tube has high TGF-B early in development
Dorsal
57
What specifies what type of neuron is formed
Amount of BMP and Shh (gradient)
58
What encases the grey and white matter
Connective tissue
59
Where is the growth cone of a neuron
Axon
60
What does the growth cone control
Sensory and locomotor
61
What forms a synapse with the target tissue
Growth cone
62
What recieves impluses on the neuron
Dendrites
63
What do synapses connect
One neuron to another
64
Purpose of myelination
Prevents dispersal of electrical signals (faster)
65
Schwann cells
Wraps plasma membrane around the axon
66
Is gray matter myelinated
No
67
Is white matter myelinated
Yes
68
Glial cell job
Produce roads for migrating neurons to take (recognition, adhesion, direction of migration)
69
What direction do neurons travel
Towards a factor
70
Site of proliferation
Ventricular zone
71
How thick is the ventricular zone
One cell layer (cell goes through cell cycle, daughter migrates and remaining cell divides again)
72
What side of the neural tube does mitosis occur on
Luminal side
73
What direction are initial divisions
Horizontal
74
Where do the daughter cells of horizontal division attach
Luminal side
75
What direction is division as neuroepithelial cells differentiate
Vertical, daughter cell migrates
76
What cells does spinal cord neuronal differentiation form
Layers of the brain and spinal cord (must migrate)
77
Where do the earliest dividing cells of the spinal cord migrate
To closest layers
78
Where do the later dividing cells of the spinal cord migrate
Migrate farther
79
What do differentiated cells of the spinal cord migrate through
Preceding layers
80
Where do the axons of daughter cells extend to
Marginal zone
81
Where is the body of daughter cells
Intermediate zone
82
What zone is closest to the lumen
Ventricular zone
83
What part of the cell is in gray matter
Body
84
What part of the cell is in white matter (marginal zone)
Axon
85
Where does brain neural differentiation occur
Cerebellum (becomes cerebral cortex)
86
What part of the neural tube does the brain develop from
Cranial
87
What part of the neural tube does the spinal cord develop from
Posterior
88
What does the central canal of the brain form
Fluid filled spaces ((ventricles)
89
What are clusters of neurons in the brain called
Nuclei
90
How do layers of neurons interact
Horizontal layers interact
91
Neuroblast migration in brain
Migrate through white matter to form a second layer of neurons at the surface (gray matter)
92
Another name for gray matter
Neocortex, cerebral cortex
93
How many layers of neuronal cell bodies are formed in the brain
6, each layer received imput from a different region
94
How many regions is the brain divided into horizontally
More than 40
95
Neurotropins
Chemotactic factors which are chemattractive and chemorepulsive towards neurons (chemotaxis)
96
NGF
Nerve growth factor
97
BDNF
Brain derived neurotropic factor
98
CDNF
Conserved dopamine neurotropic factor
99
GDNF
Glial derived neurotropic factor
100
NT3, NT4.5
Neurotropins 3 and 4/5
101
What do neurotropins affect
Migration, neuronal cell death and synapse formation
102
What neurotropin is responsible for Huntingtons disease
BDNF
103
How does BDNF cause Huntingtons disease
Unregulated production
104
When are adult forms of the neocortex completed
Mid childhood
105
How many neurons are added to the brain per minute
250,000
106
How many synapses are formed per second during the first few years
30,000
107
Cause of microcephaly
Too little proliferation, failure of brain to grow at normal rate
108
Diagnosis of microcephaly
3 SD below the mean
109
Cause of macrocephaly
Too much proliferation
110
Diagnosis of macrocephaly
2 SD above the mean
111
When is myelination of the brain completed
Adulthood
112
Neural crest regions
Trunk
Vagal
Cranial
Cardiac
113
Initiation
Interactions between neural plate and presumptive epidermis
114
How do neural crest cells undergo epithelial to mesenchymal transition
Migrate individually (no more e-cadherin)
115
What stimulates the epithelial to mesenchymal transition of neural crest cells
Wnts, BMPs, FGFs
116
What do neural crest cells become
PNS, adrenal medulla, melaoncytes, facial carilage, dentine in teeth
117
What does the PNS become
Schwann cells
Neuroglial cells
Sympathetic nervous system
Parasympathetic nervous system
118
What is considered the 4th germ layer
Neural crest cells
119
What is the vagal region names after
The vagal nerve
120
What does the vagal nerve innervate
The heart
121
Another name for cranial neural crest
Cephalic
122
What is created from the cranial neural crest
Facial cartilage and bone
Cranial neurons
Glia
Connective tissue
123
What do cranial neural crest that have entered the pharangeal arches form
Thymic cells
Odontoblasts of tooth primordia
Bones of the middle ear and jaw
124
How many pharangyeal arches are there
4
125
What do NC cells contribute to in facial development
```
Skeletal elements (face, hyoid)
Cartilage elements (trachea)
Inner ear bones
Cranial nerves (V, VII, IX, X)
```
126
Why do they say the face reflects the brain
Made up of the same cells
127
Where does the heart begin to form
In the neck region below the pharangyeal arches
128
What do cardiac NC form
Endocardial lining, septum between aorta and pulmonary artery (divides truncus arteriosis)
129
What do humans who have congenital heart defects also have defects of
Parathyroid, thyroid and thymus gland
130
Why do humans have defects in these areas because of heart defect
Human cardiac NC cells also migrate to arches 3 and 4 which contribute to these parts
131
Two migration pathways os NC cells
Ventrolateral
| Dorsolateral
132
Ventrolateral pathway
Early migration, into and through the anterior (not posterior) half of the somite
133
What does the ventrolateral differentiate into
Dorsal and root ganglia
134
Dorsolateral pathway
Later migration, travel between ectoderm and somite mesoderm, later move into epidermis
135
What does the dorsolateral pathway form
Melanocytes
136
Where is the dorsolateral pathway
Between epidermis and dermis (colonize hair and skin follicles)
137
What do vagal and sacral neural crest cells generate
Parasympathetic (enteric) ganglia of the gut
138
What does surface ectoderm become
```
Epidermis
Hair
Nails
Sebacous glands
Olfactory epithelium
Mouth epithelium
Lens, cornea
```
139
What does the mouth epithelium become
Anterior pituitary
Tooth enamel
Cheek epithelium
140
Somites
Whirls of mesoderm on both sides of the neural tube
141
Mesodermal layers
Somatic mesoderm on top
Coelom in middle
Splynchic mesoderm on bottom
142
Where do migrating mesodermal cells go
Form a layer of the mesoderm
143
Where are more organized structures located
Anterior, eventually posterior will become more specialiezed
144
What is notochord made of
Mesoderm
145
Another name for notochord
Chordomesoderm
146
As you more farther from the neural tube, _____ increases
BMP
147
Mesodermal structures
```
Muscle
Bone
Vertebrae
Tendon
Kidney
Primordial germ cells
```
148
What does paraxial mesoderm become
Head and somite
149
What does the somite become
```
Sclerotome
Syndotome
Myotome
Endothelial cells
Dermatome
```
150
What will sclerotome become
Cartilage
151
What will syndotome become
Tendons
152
What will myotome become
Muscles
153
What will dermatome become
Dermis and skeletal muscle
154
What will lateral plate mesoderm become
Splanchnic
Somatic
Extraembryonic
155
What will splanchnic become
Circulatory system
156
What will somatic become
Body cavity
157
What will intermediate mesoderm become
Kidney and gonads
158
How are mesodermal subdivisions specified
Amount of BMP
159
What has the most BMP4
Lateral mesoderm
160
What do different BMP expressions cause differences in
Foxhead family expression
161
What does expression of different fox result in
Different mesodermal fates
162
Somitogenesis
Somite formation
163
How do somites form
Paraxial mesoderm organizes into whirls
164
What direction does somite formation happen in
Anterior to posterior
165
Sometomere
Forming ball, only called the somite when the ball is fully formed
166
Somitogenesis steps
```
Periodicity
Fissure formation
Epithelialization
Specification
Differentiation
```
167
Periodicity
Reacting to time point
168
Fissure formation
Separates ball of mesoderm
169
Epithelialization
Epithelial layer surrounds the somite
170
Specification and differentiation
Tells the cells what to become
171
Mechanism of somite formation
Clock (Wnt) and wave (notch)
| Cyclic activation of notch and wnt pathways
172
What happens when a new border is transplanted in the middle
New border causes extra somite
173
Where is the signal to make somites long before somite formation
Paraxial mesoderm
174
What is responsible for creating the border
Notch
175
What happens to mesenchymal mesoderm during epithelialization
Transforms into a hollow ball
176
Polarization of cells during epithelialization
```
Sub apical surface (inward)
Basal membrane (outside)
```
177
Where are tight junctions formed during epithelialization
Between basal lamina
178
What is synthesized during epithelialization
Extracellular matrix proteins (fibronectin, n-cadherin)
179
What promotes epithelialization
Fibronectin
| N-cadherin
180
Fibronectin
ECM organizing protein
181
N-cadherin
Adhesion protein
182
True or false, all somite will form the same thing
False, they are identical but form different things
183
When does specification of somites occur
Before somatogenesis
184
What is somite tissue specified by
Neural tube floor plate (Shh)
Neural tube roof plate (Wnt)
Epithelial ectoderm (BMP)
Lateral plate mesoderm (FGF)
185
What do somite identify according to
Hox gene expression
186
True or false, somites always retain their hox gene expression
True
187
When are hox genes turned on
Before somite formation
188
Major somite components
Sclerotome
Myotome
Dermatome
189
Scleratome derivatives
Vertabrae, ribs and ribcage
190
Myotome derivatives
Musculature of the back, ribs, and limbs
191
Dermatome dertivatives
Dermis of the back
192
Minor components of the somite
Syndetome
| Cells that generate vascular cells in the dorsal area
193
Syndetome derivatives
Tendons
194
What does the syndetome arise from
Dorsal most sclerotome cells
195
Sclerotome derivatives
Cartilage of the vertabrae and part of the ribs
196
Where does the sclerotome go during development
Towards the neural tube
197
Dermamyotome
Remaining potion of the somite containing precursors for the dermatome and myotome
198
Mesenchymal connective tissue of the skin
Dermis
199
Types of myotome
Primaxial and abaxial
200
Primaxial (epaxial) myotome
Intercostal muscles of the ribs, deep muscles of the back (core)
201
Abaxial (hypaxial) myotome
Body wall, limbs, tongue
202
Where is Shh high and why
Sclerotome
| From the notochord and floor plate
203
What do sclerotome secrete
Pax1 (transcription factor)
204
What does Pax1 lead to
Cartilage and vertebrae formation
205
What does dermatome secrete
Neurotropin 3 and Wnt1 from roof plate (shh antagonist)
206
Where does myoD come from
Notochord
207
What does myoD signal
Cells to become muscle cells
208
Steps of muscle determination
1. Myotome cells detemination (express myoD)
2. Multiplication of dividing myoblasts
3. Multiplication stops, cell alignment
4. Initial myotube formation (fusion, differentiation)
5. Myotube maturation, fusion of most remaining myoblasts
6. Muscle fiber and stem cell maturation
209
Factors during determination
Wnt, Shh, MyoD, Myf5
210
Factors during multiplication
FGF
211
When does muscle contraction begin
Maturation
212
What is alignment mediated by
Membrane glycoproteins and cadherins
213
Stem cells of muscle
Satellite and mesenchymal SC
214
Why cant the myotube divide
Has multiple nuclei
215
What is the skeleton generated from
Somites (vertabrae)
Lateral plate mesoderm (limb bones)
Neural crest cells (brachial arch, cranial facial bones)
216
Ossification types
Intramembraneous
| Endochrondrial
217
Intramembraneous
Direct conversion, mesenchyme to bone
218
Endochrondrial
Mesenchyme to cartilage to bone
219
What undegoes intramembraneous
Dermal bones (face, patella, clavicle)
220
What undergoes endochrondrial
Long bones
221
What is a chrondrocyte
Cartilage cell
222
What happens when chondrocytes proliferate
Form cartilage model, secrete cartilage specific ECM
223
What happens after shift of the ECM
Increased mineralization
| Secrete angiogenesis factor VEGF
224
Bone/cartilage differentiation
Mesenchymal cells --> prechondrocyte --> Reserve chondrocyte --> proliferating chondrocyte --> prehypertrophic chondrocyte --> hypertrophic chondrocyte --> preosteoblast --> osteoblast
225
What does the notochord induce the mesenchyme to attract in vertabrae formation
and how many somites involved in vertebrate formation
Sclerotome cells
2
226
What do sclerotome cells become
Cartilage
227
What do sclerotomes split into and where are they located
Rostral (posterior) and caudal (anterior) segments
228
Purpose of resegmentation and what is it
Enables muscles to coordinate movement
| -Nerve grows in middle of rosteral and caudal and reaches to muscle
229
What is induced by myotome cells to form tendon
Syndetome
230
What induces scleraxis
Fgf8
231
Where is scleraxis induced
First row of sclerotome cells
232
What blocks scleraxis transcription
Sclerotome cartilage precursors
233
What expresses scleraxis
Progenitors of the tendons
234
What part of the sclerotome forms the syndetome
Most dorsal part
235
Why does a chick without the egg not develop bones
No calcium salt deposition
236
Development of vertebrae kidney
1. GDNF released from metanephrogenic mesenchyme and picked up by receptors on nephric duct
2. Buds formed on nephric duct
3. Bud connects to metanephrogenic mesenchyme
4. Kidney formation
237
What do metanephric tubules and ducts form
- Efferent ducts
- Epididymus
- Vans deferens
238
Reciprocal inductions of the ______ and ______ result in formation of the nephron
Ureteric bud, metanephrogenic mesenchyme
239
Functional unit of mammalian kidney
Nephron
240
How are wnts critical in kidney development
Important in aggregation of mesenchyme to form kidneys
241
Coelomic cavities
Pocket that different organs will fit into
242
Somatic lateral plate layer
Associates with ectoderm, contributes to connective tissue of body wall and limbs
243
Visceral lateral plate layer
Associates with endoderm
244
Types of coelomic cavities
- Plural
- Pericardial
- Peritoneal
245
Plural
Lungs
246
Pericardial
Heart
247
Peritoneal
Digestive organs
248
What displaces pleuropericardial folds
Growing lungs
249
______ forms as separate sac
Pericardium
250
Heart forming cells
Cardiogenic mesoderm
251
What induces the cardiogenic mesoderm
Endodermal signals (BMP)
252
What inhibits cardiogenic mesoderm
Notochord (noggin and chordin)
253
What is inhibited by the neural tube
Wnts
254
What do wnts promote
Blood vessel formation (hemangiogenic mesoderm)
255
Where do heart forming cells migrate to
The midline
256
What specifies heart tissue
BMP and Wnt
257
Anterior lateral plate mesoderm
Cardiogenic mesoderm (heart)
258
Posterior lateral plate mesoderm
Hemangiogenic mesoderm (blood vessels, blood)
259
What inhibits wnt
DKK
260
What inhibits BMP
Noggin
261
Determination of anterior and posterior of the heart
Retinoic acid
262
Gene in charge of heart cell differention
GATA4
263
What controls heart looping
Nodal
264
What does heart tube looping convert
Anterior posterior to left right
265
What does hand 1 control
Left ventricle
266
What does hand 2 control
Right ventricle
267
What does the septum grow towards
Center portion (endocardial cushion)
268
What is the purpose of the foramen ovale
Allows for shunt, closes at birth
269
Purpose of shunt
Send blood from right to left atrium to bypass the lungs
270
Constraints of circulatory system
Physiological
Evolutionary
Physical
271
Physiological constraints
Need to get nourishment in and waste out. Must be difference between vessels in embryo and adult
272
Where do microglial cells form
In the vessels of the yolk sac. They migrate to the brain
273
Evolutionary constraints
Still have evolutionary remnants of past ancestors (we still nourish yolk sac, we still have fraction of aortic arches). Shows we have evolved from lower structures
274
Physical constraints
Balance between very large tubes and very small tubes. Large tubes allow for large amount of volume to pass thrugh quickly but no diffusion. Diffusion in small tubes but rate of travel is slow
275
When does the heart primordia start beating
After first circulatory loop is established
276
Vasculogenesis
First process of blood vessel formation, a capillary network of blood vessels is created from the lateral plate mesoderm
277
Angiogenesis
Second process of blood vessel formation, primary capillary networks are remodeled and veins and arteries are made
278
When does angiogenesis occur
Cancer and gestation
279
What do hemangioblasts in the splanchnic mesoderm condense to form in vasculogenesis and angiogenesis
Blood islands
280
What surrounds the blood islands
Endothelial cells (mesenchyme inside)
281
Where is VEGF gradient released from during blood vessel formation
Mesenchyme near blood islands
282
What does VEGF induce
Endothelial cells to form from arteries
283
What induces veins
Arteries
284
VEGF
Vascular endothelial growth factor
285
What do we need to form blood vessels
VEGF
286
What do blood vessels grow towards
VEGF
287
Where is ephrin b4 found
Veins
288
Where is ephrin b2 found
Arteries
289
What causes fusion of artieries and veins
ephrin b2 and 4 interact
290
Where does fusion of arteries and veins occur
Border
291
Abnormal blood vessel development diseases
Preclampsia
| Cancer
292
Preeclampsia
Not enough VEGF, dysfunction of endothelial cells (no VEGF binding to receptor)
293
How many RBC replaced daily
10^11
294
What is capable of generating all blood and lymph cells
Pluripotential Hematopoietic stem cells (HSC)
295
What do HSC generate
Series of intermediate stem cells with potencies restricted to cell lineages
296
Where does embryonic hepatoisis take place
Blood islands
297
Where are definitive hemopoitic cells derived from
Splanchnic lateral mesoderm surrounding the aorta
298
Where do hemopoitic cells move to
Fetal liver and then bone marrow
