Third Exam Flashcards
(388 cards)
1
Q
What parts of the developing embryo are part of the ectodermal layer
A
neural tube
2
Q
What does the neural tube develop into
A
CNS and some PNS
3
Q
What cell activities occur during ectodermal organs formation
A
multiplyin, migrating, changing shape
4
Q
What composes the CNS
A
brain and spinal cord
5
Q
What parts of the PNS does the ectodermal layer compose
A
neurons connecting CNS with skin, muscles, ect
6
Q
What are the 3 sources of ectoderm
A
original layer, scattered ectoderm cells, and the neural tub
7
Q
how many neurons make up the nervous system
A
100,000,000,000
8
Q
How many glial cells make up the nervous system
A
1,000,000,000,000
9
Q
how many neurons are made within a minute
A
250,000
10
Q
What does the development of the spinal cord start off with
A
neural tube is a single layer
11
Q
What type of cells compose the neural tube
A
neuroepithelial cells
12
Q
What kind of cell potency do the neuroepithelial cells have
A
pluripotent stem cells
13
Q
What kind of capacity for proliferation do the neuroepithelial cells have
A
virtually unlimited self-renewal and generation of more committed progenitor cells
14
Q
neuroblasts with continued proliferation produce what
A
neurons
15
Q
Glioblasts produce what
A
glial cells
16
Q
what determines which progenitors and ultimate fates
A
timing and induction by the combination of growth factors at the present time
17
Q
what determines the timing of cells
A
it switches which it makes more at different times
18
Q
how does induction signal changes
A
growth factors and neurotrophic factors
19
Q
does the neural tube exist in an adult
A
yes
20
Q
where does the neural tube exist in an adult
A
the lumen of spinal cord
21
Q
Do neuroepithelial stem cells persist in the adult
A
yes allowing for cell replacement/ capacity for regeneration
22
Q
Are there neuroblast and glial blast cells in adults
A
yes, but limited capacity
23
Q
What is the idea for figuring out NTF and alzheimers
A
in figuring out the right NTF, we could stimulate them to regenerate faster
24
Q
What happens initially to the neural tub
A
neuroblasts move out from the tube to some distance and stop
25
Why do the cells stop
they have congregated in a thick layer
26
What is this layer called
mantle layer
27
What occurs to the cells in the mantle layer
they eventually stop dividing and sprout numerous extensions
28
What are these extensions called
neurites
29
What do the neurites extension form
axon and dendrites
30
What occurs after neurites are formed
another round of division occurs by the neural tube
31
What does the second round of division produce
glioblasts
32
What do the glioblasts do after being formed
travel through mantle layer to marginal layer where they wrap around the axons
33
As they wrap axon what do they make
oligodendrocytes
34
What do oligodendrocytes make
myelin
35
What color is myelin
white matter
36
The marginal layer forms what layer
white layer
37
What is the gray layer
mantle layer
38
Why is the mantle layer gray
no myelin
39
What other thing do some of the glioblasts develop into. What is the second glial cell
astrocytes
40
What do astrocytes make
meninges
41
What do microglia do
they are scattered through adults and are the immune system of the nervous system
42
What is the third glial cell
microglia
43
What produces microglia cells
cells come from mesenchyme of mesoderm, not glialblasts
44
as more cells are added, cells in the gray matter form what
layers
45
what direction of the embryo do these layers form
dorsal ventral axis
46
What occurs to the white and gray matter during embryogenesis
increase in thickness as the cells proliferati
47
What does the thickening of the white and gray matter cause/create
fissures in the spinal cord
48
Along with the astrocytes, what other cell forms a protective layer around the spinal cord
mesenchymal cells
49
What are the protective layer around the spinal cord called
meninges
50
The layers in the gray matter are arranged how
functional flow of neurons in the reflex arc
51
What causes the neurons to form the reflex arc/ layers of the gray matter
overlapping gradients of inducers
52
What are the two chemical inducers involved in the formation of the reflex arc
SHH molecule and BMP4
53
What produces SHH molecule
notocord and floor plate
54
What does SHH stand for
sonic hedge hog
55
What does SHH signal
motor neuron development
56
What produces BMP4
roof plate and dorsal ectoderm
57
What does BMP4 signal
development of sensory neurons
58
Cells that don't receive any signaling/ or equal parts of mixed signaling develop into what
the default pathway of creating interneurons
59
How are the fissures created
cells piling up on the side and those cells on the dorsal later side not dividing
60
What is a chief difference of the development of the brain from the spinal cord
lumen of neural tube expands into tunnels (not tube)
extra proliferation of cells in certain regions
some invagination and evagination occur
some mantle cells migrate through white marginal layer to form a new outermost layer
61
What are the tunnels created by lymen of neural tube expansion
ventricles
62
What do the ventricles of the brain contain
cerebral spinal fluid
63
What does the extra proliferation of cells in certain regions create
lobes of brain
64
What does the invagination and evagination occurring create
sulci and gyri (ridges and grooves)
65
The spinal cord has how many layers of gray and white matter
2 (one of each)
66
What layer is the white layer
outside layer
67
What layer is the gray layer
inside/ most central layer
68
In the brain, how many layers are there
3
69
What are the three layers of the brain
mantle layer, marginal, and cortex
70
Is the cortex layer gray or white matter
gray
71
Why is the cortex layer a gray layer
cell bodies and nuclei are present
72
What occurs to the anterior head end of the neural tube
cell proliferation
73
What does cell proliferation produce
3 bulges
74
What are the 3 bulges
prosencephalon
mesencephalon
rhombencephalon
75
What does the prosencephalon produce
front brain
76
What does the mesencephalon produce
middle brain
77
What does the rhombencephalon produce
hind brain
78
What part of the PNS is produced by the ectoderm
efferent and motor axons which exit the spinal cord
79
Where do the efferent and motor axons exit the spinal cord
through the intervertebral foramina via its ventral roots
80
How many pairs of spinal nerves are ther
31
81
What do the 3 primary bulges give rise to
secondary bulges
82
What does the prosensephalon give rise to
telencephalon
83
What does the mesencephalon give rise to
diencephalon
84
What does the rhombenceophalon give rise to
metencephaon and myelencephalon
85
What does the telencephalon give rise to
far brain
86
What composes the far brain
cerebrum
87
What does the diencephalon produce
across brain
88
What composes the across brain
thalamus, hypothalamus, optic cup,
89
What is the optic cup
an evaginated area
90
What is the optic cup involved in functionally
making the retina of the eye, makes only the retina not the other parts.
91
Why does the optic cup development from the ectoderm/brain make sense
retina is composed of neurons and optic nerve that directly connects to the brain
92
What does the myelencephalon produce
spinal cord brain
93
What is the spinal cord brain
medulla
94
What does the metencephalon produce
after brain
95
What composes the after brain
cerebellum
96
Where do neural crest cells originate
stranded cells, cells from the crests of neural fold at he junction of the neural plate, and the epidermal ectoderm
97
Where do the stranded cells come from
when the neural tube fuse, the neural plate to neural plate expresses n-cam and epidermis to epidermis express e-cadherin. cells that do not express either are stranded
98
What properties do neural crest cells express
stem cell properties
99
What are the 3 movements that neural crest cells perform
dorsolateral movement
dorsoventral movement
some stay in the vicinity
100
How do neural crest cells gain movement ability
lose their connections and adhesiveness to the ectodermal layer and become migratory
101
What does the dorsolateral movement produce
plug themselves into the epidermis to get melanocytes
102
What do cells undergoing dorsoventral movement produce
develop into different organs
103
What happens to the cells that remain close to the neural tube
aggregate into the dorsal root ganglia
104
What is the first blood vessel created
dorsal aorta
105
How do we determine what cell fates these cells have
injecting with dye and see where the cells end up
106
What are the different fates of the neural crest cells
```
sensory neurons and glial cells of PNS
nose and ear cartilage
some facial bones
epithelium of cornea
teeth dentin layer
melanocytes
hormone-producing adrenal glands
arterial smooth muscle
```
107
What 2 hypothesis are there to identify NC Fate
pluripotency idea and selection process idea
108
What is the pluripotency idea
all neural crest cells are pluripotent, it just ended up in that location and became that
109
The pluripotency idea says fate is determined when
in the end
110
What is the selection process idea
neural crest cells fate are determined at the start, they have been programmed since the beginning
111
What idea supports the process of neural crest fate
both, mixture of both ideas
112
Why do cells migrate in a certain direction
correct SAM and substrate molecules
| soluble chemotactic factors, CTF receoptors
113
What does SAM allow
allows cells with correct SAM to follow the path of substrate to where it is suppose to be
114
What does having the right neurotrophic factor allow
chemotaxis occurs and cell moves in right direction of hishest concentration, cells have specific neurotrophic factors
115
What neurotrophic factor develops melanocytes
steel
116
What secretes steel
epidermis cells
117
What factor develops neural crest cells into enteric ganglion
GDNF
118
What produces GDNF
gut endoderm
119
What is the funcion of enteric ganglion
coordinates intestinal motility
120
What is a problem associated with mutated GDNF
Hirschspung Disease in birds
121
What is another name for Hirschspung Disease
congenital megacolon
122
What occurs due to mutated GDNF
serious enteric obstruction and distention due to no enteric ganglia
123
What are ectodermal placodes
patches, islands, of ectoderm formed by the cells taking on columnar, less flat shape
124
Where are ectodermal placodes found
regions of the developing head
125
How many ectodermal placodes are there
3 pairs (6 total)
126
What causes the formation of ectodermal placodes
induced by the underlying parts of the developing brain
127
What are the 3 placodes
otic
lens
nasal
128
What do placodes make
paired structures like eyes, ears, nostrils
129
What does the otic placode produce
inner ear
130
What chemical morphogen causes the production of the otic placode
FGF19 and Wnt8c
131
What produces FGF19 and Wnt8c
underlying rhombencephalon of the developing brain
132
What occurs to the cells that receive the chemical morphogens
they get taller and invaginate
133
What occurs to the invagination of the otic pit
otic pit deepens, and the edges of the pit fuse together
134
What does this fusion of the edges produce
vesicle
135
What occurs to the vesicle with time
as the cell multiply, the vessicle become short elongated tube
136
What is this short elongated tube eventually become
cochlea and semicircular canals
137
the cochlea and semicircular canals make up what
the inner ear
138
What functional role does the cochlea make up
hearing
139
What functional role do the semicircular canals make up
equilibrium
140
What occurs immediately following the invagination that leads to vesicle
the pit closes up
141
What happens after the pit closes up
it reinvaginates
142
What does the reinvagination produce
the external ear canal
143
How is the middle ear formed
the endoderm of the pharynx evaginates to connect to the middle ear
144
What does this connection create
ecto endo meeting point
145
Where do the bones of the ear come from
the mesoderm
146
What does the lens placode produce
the eye
147
What induces the formation of the eye
optic cup from the diencephalon
148
What occurs first following induction
invagination to produce lens vessicle.
149
Cells on the ventral side of the vesicle are what
stem cells
150
What do these stem cells do
multiply to produce layers upon each other, "onion like" layers
151
What occurs following proliferation
the lens vesicle induces the optic cup to surround the vesicle
152
What type of interaction do the lens vesicle and optic cup have
reciprocal interaction/ coordination
153
What occurs when the optic cup surrounds the lens vesicle
lens has been eye
154
How does the optic cup surround the lens vesicle
new layers of cells continue to form around the lens
155
Why is it important that the optic cup stops proliferating at some point
so it doesnt cover completely to leave an opening for the pupil
156
What occurs following the proliferation around the lens vesicle
proliferation of the optic cup occurs to produce multiple layers
157
What do these multiple layers create
the retina, including rods and cones
158
Does the optic cup separate into layers the entire way around the eye. Why or Why not
no. it remains attached in the back to serve as the conduit for the optic nerve and artery
159
What forms the optic nerve
ganglion cells in retina
160
Where does the sclera and choroid come from
mesenchyme cells of the mesoderm
161
What attracts the mesenchyme cells
optic cup attracts them
162
what occurs to the lens placodes when finished
they move medially towards the center of the face, not all the way
163
What occurs to the odic placodes when finished development
they remain in spot
164
What occurs to the nasal placode when finished
moves medially all the way to the center of the face
165
What does the nasal placode form
the nostrils
166
what layer of the brain produces the nasal placode
endoderm and telencephalon
167
What is the first step of nasal placode development
invagination occurs
168
What follows following invagination
no vessicle is formed, but the pit gets deeper and deeper
169
How far do the pits get deeper
until they come in contact with the oral cavity
170
How far forward on the face do the nasal placodes move
until the walls of the pit meet
171
What causes the nasal placodes to move forward
development of maxilla
172
What does the shared wall between the two pits form
nasal septum
173
In some cases when the maxilla bones fail to fuse, what is caused
cleft pallet
174
What is the epidermis made of
stratified epithelium
175
What is the dermis made of
collagen/fibroblasts
nerves
circulatory system and blood cells
176
Where do collagen and fibroblasts come from
mesenchym scattered cells
177
Where do nerves come from
neural crest
178
Where do circulatory system and blood cells come from
mesoderm
179
What are derivatives of the skin
hair, nails, feathers, scales, antlers, hooves, pads
180
do horns =antlers
no, horns are bone and antlers are ectoderm
181
What induces the skin derivatives
mesenchyme cells in the underlying dermis
182
What produces a hair bud
proliferation and invagination
183
What causes the cells to invaginate
mesenchyme cells secrete FGF10
184
What occurs to the knot of mesenchyme cells
proliferating cells surround it
185
What has formed once the invagination and mesenchyme is surrounded
hair follicle
186
How is the hair shaft formed
multiplication
187
What forms the capillaries that supplies the epidermis
elongate to the follicule from the mesoderm
188
Where do sebacious glands come from
evagination of the hair follicule
189
Are sebacious glands connected to the hair follicule
yes
190
How are glands produced
proliferation and invagination of ectodermal cells induced in the proper locations
191
Once invagination of the ectodermal cells occurs, what happens
branching occurs (mammary glands) to form interconnected branches to each other
192
What causes the branching to occur
TGF-beta
193
What does TGF-beta do
stimulate proliferation
prohibits branching
inhibits TGF-beta
194
When can cells begin to branch again
once they are outside of TGF beta zone
195
To produce tree like branching what occurs
the process repeats in cycles randomly
196
What does the endodermal layer create
gut lining
197
What makes up the gut lining
inner epithelium only
198
What other GI tract tissues are present
blood vessels and smooth muscle cells
enteric neurons
connective tissue
199
Where does the blood vessels and smooth muscle cells come from
mesodermal layer
200
Where does enteric neurons come from
neural crest
201
Where does connective tissue come from
mesenchyme
202
What cellular movement creates foregut and hindgut
ventral folding at the cranial and caudal ends
203
What maintains the connection of gut to the yolk sac
vitelline duct
204
What carves the embryo off the yolk sac
ventral closure
205
What occurs following ventral folding at the anterior and posterior ends of the embryo
the endoderm and ectoderm contact each other
206
The location where the endoderm and ectoderm come in contact at the anterior end is called what
stomodeum
207
The location where the endoderm and ectoderm come in contact at the posterior end is called what
proctodeum
208
THe proctodeum develops into what
anus
209
The stomodeum develops into what
mouth
210
What is the function of the stomodeum and proctodeum
temporarily prevent amniotic fluid from getting inside the embryo
211
The anterior end of the gut tube forms what
esophagus
212
Between what layers do the tubes form
mesoderm and endoderm
213
Following the esophagus what forms next
stomach
214
Behind the stomach what forms
rudiment of the small intestine
215
Following the small intestine what forms
colon
216
What causes the formation of these structures
chemical morphogens
217
What chemical morphogens causes the formation of these organs
BFGF and noggin/OtX2
218
What secretes BFGF
posterior end of the embryo, near proctodeum
219
What secretes noggin/OTX2
anterior end of the embryo, near stomodeum
220
What are the gut derivatives
```
trachea
liver
pancreas
salivary glands
urinary bladder
```
221
What causes the formation of the trachea
invagination of esophagus occurs
222
On what surface does the invagination occur
ventral surface
223
What occurs following invagination to form the trachea
proliferation of cells/involution
224
What results due to proliferation of cells
bud enlarges
225
How far does this occur down the esophagus
part way starting at the pharynx
226
What occurs following the formation of a bud
the trachea and esophagus seal over to create two separate but conjoined tubes
227
Following the formation of the trachea, what occurs to the trachea
it splits into two primary bronchi
228
What occurs to the two primary bronchi
split into smaller branches, which split into smaller and smaller branches
229
What does the splitting of the bronchi form
respiratory tree
230
What is at the ends of the respiratory tree
alveoli
231
What are alveoli
air sacs
232
What is the future function of alveoli
gas exchange
233
What occurs in development to allow for future gas exchange
the alveoli attract capillaries
234
Do the trachea and esophagus share a similar opening
yes
235
What is the name of the shared opening
the mouth
236
What type of lining does the esophagus have
stratified squamous
237
What type of lining does the trachea have
ciliated pseudostratified columnar
238
What is the master control gene that leads to the formation of the trachea
TBX-4
239
What is tracheal esophageal fistula
where the wall between the esophagus and trachea have not closed leading to food in the lungs
240
How do alveoli attract capillaries
the capillaries branch in the direction of the alveoli sacs
241
What allows the formation of branching bronchioles and capillaries to meet
reciprocal interaction/mutual induction
242
What is the first step that leads to the formation of the liver
invagination/ bud of gut tube
243
Where does the invagination of the gut tube occur to form the liver
posterior to the stomach and just before the small intestine
244
What occurs immediately following the budding of the gut tube
it is wrapped by mesoderm
245
Why does any bud get immediately wrapped by mesoderm
because it buds into the mesoderm layer
246
What occurs to the bud following being wrapped by mesoderm
it buds more and branches into lobes
247
Does a wall form between the liver and the gut tube
no, they remain connected
248
How does the liver remain connected to the gut tube
hepatic duct
249
What else buds off the hepatic duct
the formation of the gallbladder
250
What is the function of the gallbladder
store bile made from the liver between meals
251
What sphincter is formed between hepatic duct and small intestine
sphincter of Oddi
252
What controls the formation of the pancreas
the master control gene
253
What is the name of the master control gene that controls the formation of the pancreas
PDX1
254
What is the potential therapeutic role involving PDX1
cure diabetes by switching on PDX1 to make a pancreas
255
Where does the Pancreas form first
a bud from the small intestine
256
Following the bud formation, what occurs
the bud branches
257
How does the pancrease connect to the small intestine
via the pancreatic duct
258
Following the branching of the pancreas what occurs
the pancreatic duct and the hepatic duct combine into one
259
What is the name of the combined hepatic duct and pancreatic duct
common bile duct
260
What is the structure of the pancreas, what makes it up
filled with lots of endoderm, lots of exocrin alveoli, endocrine parts and ducts
261
Where do the salivary glands form
in the region of the pharynx
262
What is the first step of salivary gland formation
buds off anterior end of gut tube
263
What occurs to the buds of the anterior end of the gut tube
they branch
264
How do the branching salvary glands remain connected to the gut tube
salivary ducts
265
What forms at the end of the branching salivary ducts
alveoli like end
266
What is the function of the alveoli like end
secrete saliva
267
What is the first step in the formation of the urinary bladder
invagination/ bud formation on the ventral surface of the hindgut
268
What occurs to the invagination forming the urinary bladder
it proliferates and extends
269
Does the developing bladder branch
no
270
What does the extending unbranched tube eventually develop into
enlarged extra embryonic sac
271
What is the name of the enlarged extra embryonic sac
allantoic sac
272
What is the function of the allantoic sac
temporary storage site for wastes
273
What does the allantoic sac develop into
intra-embryonic bulge
274
What does the intra embryonic bulge become
urinary bladder
275
What occurs to the remainder of the allentoic sac
disinegrates
276
The duct that channeled from the now bladder to previous allentoic sac is what
transitions into uractus
277
What is the uractus
connective tissue that holds the gut up
278
Why does the waste get stored outside the developing embryo
the kidneys don't work yet
279
If the uractus does not seal on the umbilical end what is formed
uractal fistula
280
What is a uractal fistula
urine dribbles out belly button
281
Following the development of the endoderm bladder what occurs
mesoderm layers onto it
allantoic sac converts into urachus
urinary bladder remains connected to the gut
282
For birds and fish, what is formed via connection of the gut and urinary bladder
cloaca
283
What is the cloaca
solid and liquid wastes and eggs exit from the one common opening
284
In mammals, what forms between bladder and gut
a partition to divide the cloaca into separate openings
285
What is the name of the partition
perineum
286
What is the perineum composed of
mesenchymal cells
287
What is the only endodermal portion of the bladder
inside lining only
288
What forms the layers around the bladder
mesodermal layers
289
on what side of the embryo are the liquid wastes
ventral
290
What side of the embryo are the solid wastes
dorsal
291
What is the new duct formed by the perineum called
urethra
292
Where are pharyngeal pouches formed
from neck region to mouth
293
What locations on the embryo are pharyngeal pouches formed
anterior end of foregut, between mouth and esophagus
294
What occurs in the phaynx region
several points, the endoderm bulges out while the ectoderm sinks in
295
What does the endoderm bulging out form
pharyngeal pouch
296
What does the ectoderm sinking in form
pharyngeal clefts
297
What does the area in between the form
pharyngeal arches
298
What composes most of the pharyngeal arch
mesoderm
299
Each pharyngeal arch has what
one blood vessel
300
What type of interaction do the pharyngeal cleft and pouch have
reciprocal interaction, they induced each other
301
What does pouch #1 develop into
the middle ear cavity
302
What is formed via the connecting pouch and cleft meeting
tympanic membrane
303
What does cleft #1 form
outer ear
304
What is created to connect the ear to the pharynx
eustacian tube
305
What do clefts #2-6 form
nothing, they disappear
306
What was the functional role of clefts #2-6
just to induce the formation of the pairing pouches
307
In fish, what occurs to the pouches and clefts
they fuse
308
What does the fusing of the clefts and pouches form
gill slits
309
What occurs to the arches in fish
they flatten
310
What is formed from the flattening arches
gills
311
What is the function of the gills
gas exchange
312
What is the believe associated between fish and humans
fish have common structures to humans proving that we are common descents
313
What phrase captures that all animals undergo replay of their history of ancestors during development
ontogeny racapulates phylogeny
314
What does arch#1 form
malleus and incus (middle ear bones), mandible, maxillax zygomatic bones, associated muscles
315
What does arch #2 form
stapes, styloid process , hyoid bone, associated muscles
316
Where is the hyoid bone
beneath the tongue
317
Where are the styloid processes
of temporal bone, beneath/anterior to ear canal
318
What does pouch #2 form
palatine tonsil
319
Where is the palatine tonsil
faces pharynx
320
What does arch #3 form
hyoid bone and associated muscles
321
What does pouch #3 form
thymus gland
322
What is function of thymus gland
maturation of T lymphocytes
323
What do arches #4-6 form
larynx and associated muscles
324
What does puch #4 form
thyroid and parathyroid glands
325
What does clefts #2-6 form
they disappear
326
What are the fates of pharyngeal pouches, clefts, and archers in other animals
different than humans
327
(view of evolutionist) What do embryos of higher organisms do in development
they pass through the adult forms of lower organisms in the course of development
328
All members of the subphylum vertebrata pass through what same stage
pharyngeal pouches
329
WHy can't gill slits be used to prove evolution
it was evolution that led them to being called gill slits
330
What did Darwin have to rely on for his evolutionary ideals
embryologists
331
What embryologist did Darwin rely on
Ernst Haeckel
332
What flaw did Ernst Haeckel use in trying to prove evolution
biased sample of embryos, only those that supported his hypothesis
333
What did Haeckel intentionally do to promote evolution
distorted his drawings to make them look even more similary
334
What did Haeckel ignore that influenced his view of evolution
ignored earlier stages of development that embryos showed greater differences
335
To christians what is the view seen by evolutionists
they are forcing the evidence to fit the preconceived conclusions rather than derive conclusions from the evidence
336
What are the 4 subdivisions of the mesoderm
axial
paraxial/segmental
intermediate
lateral
337
What is epithelial
sheets of mesoderm cells
338
What is mesenchyme
scattered cells surrounded by lots of extracellular matrix
339
What does the axial mesoderm consist of
notocord
340
What structure is the notocord
temporary, rigid cartilage-like skeleton, tube
341
How many sheets of cells make up the intermediate subdivision of the mesoderm
one
342
How many sheets make up the lateral section of mesoderm
two
343
What makes up the paraaxial region of mesoderm
somites
344
What does the notocord prove in regards to origins
evolution from amphioxus
345
What is amphioxus
a simple primitive organism that only has a notocord and paired somites
346
What is the most important function of the notocord
induces through secretion of chemomorphogen
347
What is the chemical secreted by the notocord
noggin
348
What does the noggin secreted by the notocord induce
neural tube formation
349
What is the skeletal function of the notocord
notocord cells surround neural tube
350
What does the surround of the neural tube form
vertebral column
351
What do the notocord cells persist as
part of the spongy intervertebral discs
352
What does the paraxial mesoderm consist of
initially two ridges of mesenchymal cells
353
Where are these two ridges of mesenchymal cells located
either side of the notocord
354
What occurs to the two ridges of mesenchymal cells on the sides of the notocord
divide into segments
355
What are these segments called
somites
356
What is the function of somites
induce or form other segmental, or repeated structures
357
What are the structures formed by the somites
nerves, blood vessels, ribs, vertebrae, intercostal muscles
358
Younger embryos have how many somites
fewer somites
359
Older embryos have how many somites
more somites
360
What is between the somites
space of mesoderm
361
What causes the segmentation of the somites
expression of N-cadherin in some cells
362
Expression of N-cadherin in some cells causes what
the cells to clump together to form a circle
363
What kind of circle structure is formed by the somites
a hollow ball of cells
364
With time, what occurs to the somites
they flatten
365
After the somites flatten, what occurs
cells disband and are lured away by chemical signals
366
Because cells are lured away in different directions what does this do in regards to role
head off to different fates
367
How many groups disband from the somite
4
368
What are the 4 groups that disband from the somite
sclerotome
epiaxial myotone
hypoaxial myotone
dermatone
369
What does the sclerotome cells do
surround the neural tube and notocord
370
What does the sclerotome cells surrounding the neural tube and notocord produce
vertebrae and ribs
371
What are vertebrae and ribs structure
bones
372
Where does the epaxial myotome go
it stays but proliferates
373
What does the epaxial myotome develop into
dorsal trunk muscles
374
Where does the hypaxial myotome migrate
ventro-laterally, around to ventral side and when limbs form it goes there
375
What does the hypaxial myotome develop into
ventral trunk muscles and limb muscles
376
Where does the dermotome go
above the region, under ectoderm
377
What does the dermotome develop into
the dermis
378
what is the dermis
layer directly beneath the skin
379
What determines somite cell determination
hetertopic transplantation
380
What causes heterotopic transplantion
somites develop according to new location
determined from original location
overlap of three morphogen gradients
381
What are the three morphogens used to determine paraxial mesoderm fates
SHH
BMP4
unknown identity
382
Where is SHH produced
notocord and floor plate of neural plate
383
What region of the somite does SHH interact with most
sclerotome mostly
384
Where is BMP4 produced
roof plate of neural tube and epidermis
385
Where does BMP4 contact the somite
epiaxial myotome
386
Where does the unknown identity morphogen come from
intermediate region
387
What does the unknown identity morphogen interact with the somites
hypoaxial
388
If you don't get any of the three chemical induces what does the natural route become
dermotome
