Embryology II Flashcards
Neurulation, Folding, and Development of the Nervous System
After the notochordal process approaches the prechordal
plate, the floor of the process “fuses” with the endoderm it is now called ___
notochordal plate
what is the opening that allows communication between the amniotic cavity and the umbilical vesicle
neurenteric canal
the neurenteric canal is formed where the ____ opened into the notochordal canal
primitive pit
the notochordal plate progress to the ____
notochord
which direction does the notochord transition go from
cranially –> caudally
when is there no longer a neurenteric canal
after full development of the notochord
notochordal plate cells proliferate and fold
inwards, forming the fully-developed ___
notochord
The notochord is no longer a ___ canal
hollow
what is between the notochord and the umbilical vesicle
embryonic endoderm
the ectoderm above the notochord develops into ___
neural plate
what is the stop signal for notochord development anteriorly
prechordal plate
what develops into the oropharyngeal membrane
prechordal plate
what is special about the oropharyngeal and cloacal membranes
they only have ecto and endoderm layers
what does the cloacal membrane become
anus
Small, vascularized diverticulum (outpouching) from the caudal wall of umbilical vesicle, extending into connecting stalk
allantois
what day is the allantois formed
day 18
Allantois functions in development of what
early blood formation
bladder development
uranchus
what does the uranchus become in adults
median umbilical ligament
Notochord induces overlying ectoderm to form
the neural plate is what process
neurulation
what is special about neuroectodermal cells
tall and columnar
what does the neuroectoderm give rise to
CNS
retina
other tissues from neural crest
on day __ the neural plate invaginates to form the neural groove – neural folds are found on either side of the groove
18
the neural tube is formed by ____ fusing together
neural folds
the neural tube is primordium of what
CNS
when does neurulation end
when the tube is completely closed
end of week 4
which direction do the neural crest cells migrate
dorso-laterally
what CN ganglia do neural crest cells help develop
CN V, VII, IX, X
what NS do the neural crest cells help develop
Autonomic nervous system ganglia
neural crest cell derivatives form the _____ and ____ matter
arachnoid and pia
melanocytes are derivatives of ___
neural crest cells
craniofacial bone and cartilage are derivatives of ____ cells
neural crest
Intraembryonic mesoderm proliferates to form a thick column of mesoderm on either side of the notochord beside the axis is called what
paraxial mesoderm
cuboidal masses of mesoderm on either side of the notochord, visible along the dorso-lateral surface of the embryo on each side of the neural tube
somite
somites give rise to:
axial skeleton, musculature and dermis of area
cardiogenic mesoderm gives rise to __
embryonic heart primordia
on day __ the embryonic heart primorda is formed
20
primordium of _____ appears as isolated spaces in the lateral mesoderm and cardiogenic mesoderm
intraembryonic coelom
what shape is the intraembryonic coelom formed into
single horseshoe
what are the 2 layers that the intraembryonic coelom divides the lateral mesoderm into
- somatic /parietal layer
- splanchnic / visceral layer
what layer of lateral mesoderm covers the amnion
somatic or parietal layer
what layer of the lateral mesoderm covers the umbilical vesicle
splanchnic or visceral layer
on day ___ the coelomic spaces are a continuous cavity
21
the somatic mesoderm and the overlying ectoderm later forms the body wall
somatopleure
the splanchnic mesoderm and the underlying intraembryonic endoderm later forms the embryonic gut
splanchnopleure
what is between the somatopleure and splanchnopleure
intraembryonic coelom
intraembryonic coelom develops into 3 main body cavities which are
- pericardial cavity
- pleural cavity
- peritoneal cavity
The bilaminar embryonic disc is converted into a trilaminar embryonic disc during
gastrulation
the ___ results from migration of epiblastic cells to the median plane of the disc
primitive streak
Invagination of epiblastic cells from the primitive streak gives rise to mesenchymal cells that
migrate ventrally, laterally, and cranially between the
epiblast and hypoblast
As soon as the primitive streak begins to produce mesenchymal cells, the epiblast is known as
embryonic ectoderm
Some cells of the epiblast displace the hypoblast and form
embryonic endoderm
the anterior and posterior ends of the embryo move ventrally. Also known as cranial-caudal folding
median plane
the lateral edges of the embryonic disk move ventrally. Also known as lateral folding
* The edges “roll” ventrally towards the umbilical vesicle
horizontal folding
when does embryonic folding occur
start in end of 3rd week see at 4th week
As it folds ___, the brain vesicles first begin to
appear, and a few somites are obvious
cranially
As it folds ___, the body wall is formed
laterally
Part of the endoderm of the umbilical vesicle is incorporated into the embryo as the
foregut
what is the foregut between
brain and heart
the primordium of the mouth
stomedeum
what separates the foregut form the stomodeum
oropharyngeal membrane
develops into the central tendon of the diaphragm and separates the abdominal cavity from the thoracic cavity
spetum transversum
the location of the heart changes based on what
head fold
what is primordium of the umbilical cord
connecting stalk
after lateral folding, the
connection between the midgut and umbilical
vesicle is reduced to an ___ duct
omphaloenteric duct
connective tissue; cartilage; bone
* striated and smooth muscles; heart, blood, and lymphatic vessels; kidneys;
* ovaries; testes; genital ducts; serous membranes lining the body cavities (pericardial, pleural, and peritoneal); spleen; and cortex of suprarenal glands
mesoderm derivatives
epithelial lining of the digestive and respiratory tracts, parenchyma of the tonsils
* thyroid and parathyroid glands, thymus
* liver, and pancreas, epithelial lining of the urinary bladder and most of the urethra
* epithelial lining of the tympanic cavity, tympanic antrum, and eustachian tube
endoderm derivatives
CNS, PNS; sensory epithelia of the eyes, ears, and nose
* epidermis and its appendages (hair and nails); mammary glands; subcutaneous glands; enamel of teeth; pituitary gland
* Neural crest cells – discussed previously
ectoderm derivatives
on day __ the neural plate can be seen
19
on day __ neurulation is complete with closure of neuropores
27
on day __ the cranial 2/3 of the neural tube makes the brain and the caudal 1/3 makes the spinal cord
22
The neural folds fuse at
the level of the ___ somite, proceeds cranially and
caudally
5th
