Third Exam Flashcards
What parts of the developing embryo are part of the ectodermal layer
neural tube
What does the neural tube develop into
CNS and some PNS
What cell activities occur during ectodermal organs formation
multiplyin, migrating, changing shape
What composes the CNS
brain and spinal cord
What parts of the PNS does the ectodermal layer compose
neurons connecting CNS with skin, muscles, ect
What are the 3 sources of ectoderm
original layer, scattered ectoderm cells, and the neural tub
how many neurons make up the nervous system
100,000,000,000
How many glial cells make up the nervous system
1,000,000,000,000
how many neurons are made within a minute
250,000
What does the development of the spinal cord start off with
neural tube is a single layer
What type of cells compose the neural tube
neuroepithelial cells
What kind of cell potency do the neuroepithelial cells have
pluripotent stem cells
What kind of capacity for proliferation do the neuroepithelial cells have
virtually unlimited self-renewal and generation of more committed progenitor cells
neuroblasts with continued proliferation produce what
neurons
Glioblasts produce what
glial cells
what determines which progenitors and ultimate fates
timing and induction by the combination of growth factors at the present time
what determines the timing of cells
it switches which it makes more at different times
how does induction signal changes
growth factors and neurotrophic factors
does the neural tube exist in an adult
yes
where does the neural tube exist in an adult
the lumen of spinal cord
Do neuroepithelial stem cells persist in the adult
yes allowing for cell replacement/ capacity for regeneration
Are there neuroblast and glial blast cells in adults
yes, but limited capacity
What is the idea for figuring out NTF and alzheimers
in figuring out the right NTF, we could stimulate them to regenerate faster
What happens initially to the neural tub
neuroblasts move out from the tube to some distance and stop
Why do the cells stop
they have congregated in a thick layer
What is this layer called
mantle layer
What occurs to the cells in the mantle layer
they eventually stop dividing and sprout numerous extensions
What are these extensions called
neurites
What do the neurites extension form
axon and dendrites
What occurs after neurites are formed
another round of division occurs by the neural tube
What does the second round of division produce
glioblasts
What do the glioblasts do after being formed
travel through mantle layer to marginal layer where they wrap around the axons
As they wrap axon what do they make
oligodendrocytes
What do oligodendrocytes make
myelin
What color is myelin
white matter
The marginal layer forms what layer
white layer
What is the gray layer
mantle layer
Why is the mantle layer gray
no myelin
What other thing do some of the glioblasts develop into. What is the second glial cell
astrocytes
What do astrocytes make
meninges
What do microglia do
they are scattered through adults and are the immune system of the nervous system
What is the third glial cell
microglia
What produces microglia cells
cells come from mesenchyme of mesoderm, not glialblasts
as more cells are added, cells in the gray matter form what
layers
what direction of the embryo do these layers form
dorsal ventral axis
What occurs to the white and gray matter during embryogenesis
increase in thickness as the cells proliferati
What does the thickening of the white and gray matter cause/create
fissures in the spinal cord
Along with the astrocytes, what other cell forms a protective layer around the spinal cord
mesenchymal cells
What are the protective layer around the spinal cord called
meninges
The layers in the gray matter are arranged how
functional flow of neurons in the reflex arc
What causes the neurons to form the reflex arc/ layers of the gray matter
overlapping gradients of inducers
What are the two chemical inducers involved in the formation of the reflex arc
SHH molecule and BMP4
What produces SHH molecule
notocord and floor plate
What does SHH stand for
sonic hedge hog
What does SHH signal
motor neuron development
What produces BMP4
roof plate and dorsal ectoderm
What does BMP4 signal
development of sensory neurons
Cells that don’t receive any signaling/ or equal parts of mixed signaling develop into what
the default pathway of creating interneurons
How are the fissures created
cells piling up on the side and those cells on the dorsal later side not dividing
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
What are the tunnels created by lymen of neural tube expansion
ventricles
What do the ventricles of the brain contain
cerebral spinal fluid
What does the extra proliferation of cells in certain regions create
lobes of brain
What does the invagination and evagination occurring create
sulci and gyri (ridges and grooves)
The spinal cord has how many layers of gray and white matter
2 (one of each)
What layer is the white layer
outside layer
What layer is the gray layer
inside/ most central layer
In the brain, how many layers are there
3
What are the three layers of the brain
mantle layer, marginal, and cortex
Is the cortex layer gray or white matter
gray
Why is the cortex layer a gray layer
cell bodies and nuclei are present
What occurs to the anterior head end of the neural tube
cell proliferation
What does cell proliferation produce
3 bulges
What are the 3 bulges
prosencephalon
mesencephalon
rhombencephalon
What does the prosencephalon produce
front brain
What does the mesencephalon produce
middle brain
What does the rhombencephalon produce
hind brain
What part of the PNS is produced by the ectoderm
efferent and motor axons which exit the spinal cord
Where do the efferent and motor axons exit the spinal cord
through the intervertebral foramina via its ventral roots
How many pairs of spinal nerves are ther
31
What do the 3 primary bulges give rise to
secondary bulges
What does the prosensephalon give rise to
telencephalon
What does the mesencephalon give rise to
diencephalon
What does the rhombenceophalon give rise to
metencephaon and myelencephalon
What does the telencephalon give rise to
far brain
What composes the far brain
cerebrum
What does the diencephalon produce
across brain
What composes the across brain
thalamus, hypothalamus, optic cup,
What is the optic cup
an evaginated area
What is the optic cup involved in functionally
making the retina of the eye, makes only the retina not the other parts.
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
What does the myelencephalon produce
spinal cord brain
What is the spinal cord brain
medulla
What does the metencephalon produce
after brain
What composes the after brain
cerebellum
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
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
What properties do neural crest cells express
stem cell properties
What are the 3 movements that neural crest cells perform
dorsolateral movement
dorsoventral movement
some stay in the vicinity
How do neural crest cells gain movement ability
lose their connections and adhesiveness to the ectodermal layer and become migratory
What does the dorsolateral movement produce
plug themselves into the epidermis to get melanocytes
What do cells undergoing dorsoventral movement produce
develop into different organs
What happens to the cells that remain close to the neural tube
aggregate into the dorsal root ganglia
What is the first blood vessel created
dorsal aorta
How do we determine what cell fates these cells have
injecting with dye and see where the cells end up
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
What 2 hypothesis are there to identify NC Fate
pluripotency idea and selection process idea
What is the pluripotency idea
all neural crest cells are pluripotent, it just ended up in that location and became that
The pluripotency idea says fate is determined when
in the end
What is the selection process idea
neural crest cells fate are determined at the start, they have been programmed since the beginning
What idea supports the process of neural crest fate
both, mixture of both ideas
Why do cells migrate in a certain direction
correct SAM and substrate molecules
soluble chemotactic factors, CTF receoptors
What does SAM allow
allows cells with correct SAM to follow the path of substrate to where it is suppose to be
What does having the right neurotrophic factor allow
chemotaxis occurs and cell moves in right direction of hishest concentration, cells have specific neurotrophic factors
What neurotrophic factor develops melanocytes
steel
What secretes steel
epidermis cells
What factor develops neural crest cells into enteric ganglion
GDNF
What produces GDNF
gut endoderm
What is the funcion of enteric ganglion
coordinates intestinal motility
What is a problem associated with mutated GDNF
Hirschspung Disease in birds
What is another name for Hirschspung Disease
congenital megacolon
What occurs due to mutated GDNF
serious enteric obstruction and distention due to no enteric ganglia
What are ectodermal placodes
patches, islands, of ectoderm formed by the cells taking on columnar, less flat shape
Where are ectodermal placodes found
regions of the developing head
How many ectodermal placodes are there
3 pairs (6 total)
What causes the formation of ectodermal placodes
induced by the underlying parts of the developing brain
What are the 3 placodes
otic
lens
nasal
What do placodes make
paired structures like eyes, ears, nostrils
What does the otic placode produce
inner ear
What chemical morphogen causes the production of the otic placode
FGF19 and Wnt8c
What produces FGF19 and Wnt8c
underlying rhombencephalon of the developing brain
What occurs to the cells that receive the chemical morphogens
they get taller and invaginate
What occurs to the invagination of the otic pit
otic pit deepens, and the edges of the pit fuse together
What does this fusion of the edges produce
vesicle
What occurs to the vesicle with time
as the cell multiply, the vessicle become short elongated tube
What is this short elongated tube eventually become
cochlea and semicircular canals
the cochlea and semicircular canals make up what
the inner ear
What functional role does the cochlea make up
hearing
What functional role do the semicircular canals make up
equilibrium
What occurs immediately following the invagination that leads to vesicle
the pit closes up
What happens after the pit closes up
it reinvaginates
What does the reinvagination produce
the external ear canal
How is the middle ear formed
the endoderm of the pharynx evaginates to connect to the middle ear
What does this connection create
ecto endo meeting point
Where do the bones of the ear come from
the mesoderm
What does the lens placode produce
the eye
What induces the formation of the eye
optic cup from the diencephalon
What occurs first following induction
invagination to produce lens vessicle.
Cells on the ventral side of the vesicle are what
stem cells
What do these stem cells do
multiply to produce layers upon each other, “onion like” layers
What occurs following proliferation
the lens vesicle induces the optic cup to surround the vesicle
What type of interaction do the lens vesicle and optic cup have
reciprocal interaction/ coordination
What occurs when the optic cup surrounds the lens vesicle
lens has been eye
How does the optic cup surround the lens vesicle
new layers of cells continue to form around the lens
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
What occurs following the proliferation around the lens vesicle
proliferation of the optic cup occurs to produce multiple layers
What do these multiple layers create
the retina, including rods and cones
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
What forms the optic nerve
ganglion cells in retina
Where does the sclera and choroid come from
mesenchyme cells of the mesoderm
What attracts the mesenchyme cells
optic cup attracts them
what occurs to the lens placodes when finished
they move medially towards the center of the face, not all the way
What occurs to the odic placodes when finished development
they remain in spot
What occurs to the nasal placode when finished
moves medially all the way to the center of the face
What does the nasal placode form
the nostrils
what layer of the brain produces the nasal placode
endoderm and telencephalon
What is the first step of nasal placode development
invagination occurs
What follows following invagination
no vessicle is formed, but the pit gets deeper and deeper
How far do the pits get deeper
until they come in contact with the oral cavity
How far forward on the face do the nasal placodes move
until the walls of the pit meet
What causes the nasal placodes to move forward
development of maxilla
What does the shared wall between the two pits form
nasal septum
In some cases when the maxilla bones fail to fuse, what is caused
cleft pallet
What is the epidermis made of
stratified epithelium
What is the dermis made of
collagen/fibroblasts
nerves
circulatory system and blood cells
Where do collagen and fibroblasts come from
mesenchym scattered cells
Where do nerves come from
neural crest
Where do circulatory system and blood cells come from
mesoderm
What are derivatives of the skin
hair, nails, feathers, scales, antlers, hooves, pads
do horns =antlers
no, horns are bone and antlers are ectoderm
What induces the skin derivatives
mesenchyme cells in the underlying dermis
What produces a hair bud
proliferation and invagination
What causes the cells to invaginate
mesenchyme cells secrete FGF10
What occurs to the knot of mesenchyme cells
proliferating cells surround it
What has formed once the invagination and mesenchyme is surrounded
hair follicle
How is the hair shaft formed
multiplication
What forms the capillaries that supplies the epidermis
elongate to the follicule from the mesoderm
Where do sebacious glands come from
evagination of the hair follicule
Are sebacious glands connected to the hair follicule
yes
How are glands produced
proliferation and invagination of ectodermal cells induced in the proper locations
Once invagination of the ectodermal cells occurs, what happens
branching occurs (mammary glands) to form interconnected branches to each other
What causes the branching to occur
TGF-beta
What does TGF-beta do
stimulate proliferation
prohibits branching
inhibits TGF-beta
When can cells begin to branch again
once they are outside of TGF beta zone
To produce tree like branching what occurs
the process repeats in cycles randomly
What does the endodermal layer create
gut lining
What makes up the gut lining
inner epithelium only
What other GI tract tissues are present
blood vessels and smooth muscle cells
enteric neurons
connective tissue
Where does the blood vessels and smooth muscle cells come from
mesodermal layer
Where does enteric neurons come from
neural crest
Where does connective tissue come from
mesenchyme
What cellular movement creates foregut and hindgut
ventral folding at the cranial and caudal ends
What maintains the connection of gut to the yolk sac
vitelline duct
What carves the embryo off the yolk sac
ventral closure
What occurs following ventral folding at the anterior and posterior ends of the embryo
the endoderm and ectoderm contact each other
The location where the endoderm and ectoderm come in contact at the anterior end is called what
stomodeum
The location where the endoderm and ectoderm come in contact at the posterior end is called what
proctodeum
THe proctodeum develops into what
anus
The stomodeum develops into what
mouth
What is the function of the stomodeum and proctodeum
temporarily prevent amniotic fluid from getting inside the embryo
The anterior end of the gut tube forms what
esophagus
Between what layers do the tubes form
mesoderm and endoderm
Following the esophagus what forms next
stomach
Behind the stomach what forms
rudiment of the small intestine
Following the small intestine what forms
colon
What causes the formation of these structures
chemical morphogens
What chemical morphogens causes the formation of these organs
BFGF and noggin/OtX2
What secretes BFGF
posterior end of the embryo, near proctodeum
What secretes noggin/OTX2
anterior end of the embryo, near stomodeum
What are the gut derivatives
trachea liver pancreas salivary glands urinary bladder
What causes the formation of the trachea
invagination of esophagus occurs
On what surface does the invagination occur
ventral surface
What occurs following invagination to form the trachea
proliferation of cells/involution
What results due to proliferation of cells
bud enlarges
How far does this occur down the esophagus
part way starting at the pharynx
What occurs following the formation of a bud
the trachea and esophagus seal over to create two separate but conjoined tubes
Following the formation of the trachea, what occurs to the trachea
it splits into two primary bronchi
What occurs to the two primary bronchi
split into smaller branches, which split into smaller and smaller branches
What does the splitting of the bronchi form
respiratory tree
What is at the ends of the respiratory tree
alveoli
What are alveoli
air sacs
What is the future function of alveoli
gas exchange
What occurs in development to allow for future gas exchange
the alveoli attract capillaries
Do the trachea and esophagus share a similar opening
yes
What is the name of the shared opening
the mouth
What type of lining does the esophagus have
stratified squamous
What type of lining does the trachea have
ciliated pseudostratified columnar
What is the master control gene that leads to the formation of the trachea
TBX-4
What is tracheal esophageal fistula
where the wall between the esophagus and trachea have not closed leading to food in the lungs
How do alveoli attract capillaries
the capillaries branch in the direction of the alveoli sacs
What allows the formation of branching bronchioles and capillaries to meet
reciprocal interaction/mutual induction
What is the first step that leads to the formation of the liver
invagination/ bud of gut tube
Where does the invagination of the gut tube occur to form the liver
posterior to the stomach and just before the small intestine
What occurs immediately following the budding of the gut tube
it is wrapped by mesoderm
Why does any bud get immediately wrapped by mesoderm
because it buds into the mesoderm layer
What occurs to the bud following being wrapped by mesoderm
it buds more and branches into lobes
Does a wall form between the liver and the gut tube
no, they remain connected
How does the liver remain connected to the gut tube
hepatic duct
What else buds off the hepatic duct
the formation of the gallbladder
What is the function of the gallbladder
store bile made from the liver between meals
What sphincter is formed between hepatic duct and small intestine
sphincter of Oddi
What controls the formation of the pancreas
the master control gene
What is the name of the master control gene that controls the formation of the pancreas
PDX1
What is the potential therapeutic role involving PDX1
cure diabetes by switching on PDX1 to make a pancreas
Where does the Pancreas form first
a bud from the small intestine
Following the bud formation, what occurs
the bud branches
How does the pancrease connect to the small intestine
via the pancreatic duct
Following the branching of the pancreas what occurs
the pancreatic duct and the hepatic duct combine into one
What is the name of the combined hepatic duct and pancreatic duct
common bile duct
What is the structure of the pancreas, what makes it up
filled with lots of endoderm, lots of exocrin alveoli, endocrine parts and ducts
Where do the salivary glands form
in the region of the pharynx
What is the first step of salivary gland formation
buds off anterior end of gut tube
What occurs to the buds of the anterior end of the gut tube
they branch
How do the branching salvary glands remain connected to the gut tube
salivary ducts
What forms at the end of the branching salivary ducts
alveoli like end
What is the function of the alveoli like end
secrete saliva
What is the first step in the formation of the urinary bladder
invagination/ bud formation on the ventral surface of the hindgut
What occurs to the invagination forming the urinary bladder
it proliferates and extends
Does the developing bladder branch
no
What does the extending unbranched tube eventually develop into
enlarged extra embryonic sac
What is the name of the enlarged extra embryonic sac
allantoic sac
What is the function of the allantoic sac
temporary storage site for wastes
What does the allantoic sac develop into
intra-embryonic bulge
What does the intra embryonic bulge become
urinary bladder
What occurs to the remainder of the allentoic sac
disinegrates
The duct that channeled from the now bladder to previous allentoic sac is what
transitions into uractus
What is the uractus
connective tissue that holds the gut up
Why does the waste get stored outside the developing embryo
the kidneys don’t work yet
If the uractus does not seal on the umbilical end what is formed
uractal fistula
What is a uractal fistula
urine dribbles out belly button
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
For birds and fish, what is formed via connection of the gut and urinary bladder
cloaca
What is the cloaca
solid and liquid wastes and eggs exit from the one common opening
In mammals, what forms between bladder and gut
a partition to divide the cloaca into separate openings
What is the name of the partition
perineum
What is the perineum composed of
mesenchymal cells
What is the only endodermal portion of the bladder
inside lining only
What forms the layers around the bladder
mesodermal layers
on what side of the embryo are the liquid wastes
ventral
What side of the embryo are the solid wastes
dorsal
What is the new duct formed by the perineum called
urethra
Where are pharyngeal pouches formed
from neck region to mouth
What locations on the embryo are pharyngeal pouches formed
anterior end of foregut, between mouth and esophagus
What occurs in the phaynx region
several points, the endoderm bulges out while the ectoderm sinks in
What does the endoderm bulging out form
pharyngeal pouch
What does the ectoderm sinking in form
pharyngeal clefts
What does the area in between the form
pharyngeal arches
What composes most of the pharyngeal arch
mesoderm
Each pharyngeal arch has what
one blood vessel
What type of interaction do the pharyngeal cleft and pouch have
reciprocal interaction, they induced each other
What does pouch #1 develop into
the middle ear cavity
What is formed via the connecting pouch and cleft meeting
tympanic membrane
What does cleft #1 form
outer ear
What is created to connect the ear to the pharynx
eustacian tube
What do clefts #2-6 form
nothing, they disappear
What was the functional role of clefts #2-6
just to induce the formation of the pairing pouches
In fish, what occurs to the pouches and clefts
they fuse
What does the fusing of the clefts and pouches form
gill slits
What occurs to the arches in fish
they flatten
What is formed from the flattening arches
gills
What is the function of the gills
gas exchange
What is the believe associated between fish and humans
fish have common structures to humans proving that we are common descents
What phrase captures that all animals undergo replay of their history of ancestors during development
ontogeny racapulates phylogeny
What does arch#1 form
malleus and incus (middle ear bones), mandible, maxillax zygomatic bones, associated muscles
What does arch #2 form
stapes, styloid process , hyoid bone, associated muscles
Where is the hyoid bone
beneath the tongue
Where are the styloid processes
of temporal bone, beneath/anterior to ear canal
What does pouch #2 form
palatine tonsil
Where is the palatine tonsil
faces pharynx
What does arch #3 form
hyoid bone and associated muscles
What does pouch #3 form
thymus gland
What is function of thymus gland
maturation of T lymphocytes
What do arches #4-6 form
larynx and associated muscles
What does puch #4 form
thyroid and parathyroid glands
What does clefts #2-6 form
they disappear
What are the fates of pharyngeal pouches, clefts, and archers in other animals
different than humans
(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
All members of the subphylum vertebrata pass through what same stage
pharyngeal pouches
WHy can’t gill slits be used to prove evolution
it was evolution that led them to being called gill slits
What did Darwin have to rely on for his evolutionary ideals
embryologists
What embryologist did Darwin rely on
Ernst Haeckel
What flaw did Ernst Haeckel use in trying to prove evolution
biased sample of embryos, only those that supported his hypothesis
What did Haeckel intentionally do to promote evolution
distorted his drawings to make them look even more similary
What did Haeckel ignore that influenced his view of evolution
ignored earlier stages of development that embryos showed greater differences
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
What are the 4 subdivisions of the mesoderm
axial
paraxial/segmental
intermediate
lateral
What is epithelial
sheets of mesoderm cells
What is mesenchyme
scattered cells surrounded by lots of extracellular matrix
What does the axial mesoderm consist of
notocord
What structure is the notocord
temporary, rigid cartilage-like skeleton, tube
How many sheets of cells make up the intermediate subdivision of the mesoderm
one
How many sheets make up the lateral section of mesoderm
two
What makes up the paraaxial region of mesoderm
somites
What does the notocord prove in regards to origins
evolution from amphioxus
What is amphioxus
a simple primitive organism that only has a notocord and paired somites
What is the most important function of the notocord
induces through secretion of chemomorphogen
What is the chemical secreted by the notocord
noggin
What does the noggin secreted by the notocord induce
neural tube formation
What is the skeletal function of the notocord
notocord cells surround neural tube
What does the surround of the neural tube form
vertebral column
What do the notocord cells persist as
part of the spongy intervertebral discs
What does the paraxial mesoderm consist of
initially two ridges of mesenchymal cells
Where are these two ridges of mesenchymal cells located
either side of the notocord
What occurs to the two ridges of mesenchymal cells on the sides of the notocord
divide into segments
What are these segments called
somites
What is the function of somites
induce or form other segmental, or repeated structures
What are the structures formed by the somites
nerves, blood vessels, ribs, vertebrae, intercostal muscles
Younger embryos have how many somites
fewer somites
Older embryos have how many somites
more somites
What is between the somites
space of mesoderm
What causes the segmentation of the somites
expression of N-cadherin in some cells
Expression of N-cadherin in some cells causes what
the cells to clump together to form a circle
What kind of circle structure is formed by the somites
a hollow ball of cells
With time, what occurs to the somites
they flatten
After the somites flatten, what occurs
cells disband and are lured away by chemical signals
Because cells are lured away in different directions what does this do in regards to role
head off to different fates
How many groups disband from the somite
4
What are the 4 groups that disband from the somite
sclerotome
epiaxial myotone
hypoaxial myotone
dermatone
What does the sclerotome cells do
surround the neural tube and notocord
What does the sclerotome cells surrounding the neural tube and notocord produce
vertebrae and ribs
What are vertebrae and ribs structure
bones
Where does the epaxial myotome go
it stays but proliferates
What does the epaxial myotome develop into
dorsal trunk muscles
Where does the hypaxial myotome migrate
ventro-laterally, around to ventral side and when limbs form it goes there
What does the hypaxial myotome develop into
ventral trunk muscles and limb muscles
Where does the dermotome go
above the region, under ectoderm
What does the dermotome develop into
the dermis
what is the dermis
layer directly beneath the skin
What determines somite cell determination
hetertopic transplantation
What causes heterotopic transplantion
somites develop according to new location
determined from original location
overlap of three morphogen gradients
What are the three morphogens used to determine paraxial mesoderm fates
SHH
BMP4
unknown identity
Where is SHH produced
notocord and floor plate of neural plate
What region of the somite does SHH interact with most
sclerotome mostly
Where is BMP4 produced
roof plate of neural tube and epidermis
Where does BMP4 contact the somite
epiaxial myotome
Where does the unknown identity morphogen come from
intermediate region
What does the unknown identity morphogen interact with the somites
hypoaxial
If you don’t get any of the three chemical induces what does the natural route become
dermotome
