Lecture 1/26 Flashcards
3-4 in uterus, the morula turns into the
blastocyst
blastocyst cavity called
blastocoele
blastocyst outer layer called
trophoblast (eventually becomes placenta)
blastocyst inner layer called
inner cell mass, about 100 cells (embryo develops from this)
blastocyst gets lodged onto ____ in first 3-4 days
endometrium
what occurs in 2nd week
implantation, formation of 2 germ layers
2nd week: inner cell mass develops to have a
cavity (called amniotic cavity)
2nd week: lining of the cavity closer to trophoblast and then forms the
yolk sac
amniotic cavity will become what germinal layer
ectoderm
yolk sac will become what germinal layer
endoderm
amniotic sac and yolk sac meet, and the layer is called
embryonic disk
what occurs in the 3rd week
development of 3rd germinal layer (mesoderm)
3rd week: mesoderm arrives from
embryonic disk
tail and head of embryonic disk are called
tail: caudal end
head: cranial end
midline of the embryonic disk called
primative streak
where do mesodermal cells arise from
the primitive streak cells spreading out
segmented mesoderm called
somites
thickened ectoderm is called the
neural plate
neural groove formed when
the neural plate’s edges start to curve up
neural groove ->
neural fold
neural folds keep growing and form a
neural tube
neural tube cross section has 3 layers
- ependymal layer
neural tube ependymal layer is:
the inner most layer of non-specialized stem cells (cuboidal cells
which layer has the highest rate of mitosis in the neural tube
ependymal layer
neural tube mantle layer is:
nucleated cell layer which were formed in ependymal layer and migrated out
which layer of the neural tube will eventually form the grey matter of the nervous system
mantle layer
neural tube marginal layer is:
the outermost layer formed by extensions of fibrous processes from the mantle layer
which layer of the neural tube will eventually become the white matter of the nervous system
marginal layer (when fibrous processes are myelinated)
primary enlargements occurs after
closure of the head end (anterior end) of the neural tube
3 divisions of the primary enlargements
- forebrain
- midbrain
- hindbrain
forebrain telencephalon becomes the
cerebrum
forebrain diencephalon becomes the
eye
4th week: neuro-ectoderm thickenings are called
optic primordia
optic primordia will grow and form:
a pit called the optic pit
optic pit deepens and makes a swelling which is called the
primary optic vesicle
4th week midweek (day 25) area on primary optic vesicle starts to constrict and forms the
optic stalk
the optic stalk space is continuous with
diencephalon
the sides of the primary optic vesicle will become the
RPE
the walls of the primary optic vesicle will become the
nervous retina
the edges of the primary optic vesicle will become the
epithelium of the ciliary body and into the iris
induction can lead to
induces surface ectoderm to form the lens placode
surface ectoderm will contribute to what eye structures?
lacrimal gland, epithelium of conjunctiva, epithelium of the cornea, and the (epithelium, glands and cilia) of the eyelids
primary optic vesicle invaginates in week 5 to form the
secondary optic vesicle (optic cup)
inner wall of optic cup called
pars optica
pars optica develops into
9 layers of the nervous retina
inner wall starts at ___ and goes where
starts at optic stalk and goes peripherally
anterior part of the optic cup is the
pars caeca
pars caeca will develop into
epithelium of ciliary body and iris
junction between pars caeca and pars optica will become the
ora serrata
outer wall of the optic cup will become the
RPE
defect in the optic cup called
choroidal fissure
purpose of choroidal fissure
so mesoderm can migrate into optic cup and form the primary vitreous and so the hyaloid artery can grow into it
lens pit forms the
lens vesicle
week 6, lens vesicle turns into
ball of cells (to eventually become the lens)
week6: choroidal fissure will
seal up, starting at the central optic stalk and goes both ways but CRA goes in before it fully closes
defects of the choroidal fissure called
colobome
vitreous cavity is filled with mesodermal cells which will form the
primary vitreous
secondary vitreous is formed by
retina
secondary vitreous does what to the primary vitreous
secondary surrounds primary and pushes it into a tube
week 7 the RPE and nervous part of the retina do what
start to push together (this is a weak spot in the eye)
week 7 importance
retinal organization into 9 layers
week 8 importance
angle between stalks starts to decrease (down to 105 degrees)
ependymal layer becomes the ____ of the developing retina
outer neuroblsatic layer
mantle layer becomes the ____ of the developing retina
inner neuroblastic layer
marginal layer becomes the ____ of the developing retina
fibrous layer
outer neuroblastic layer develops into the
photoreceptors (rods and cones)
inner aspect of the neuroblastic layer develops into the
bipolar and horizontal cells
some cells migrate from neuroblastic layers
from outer neuroblastic to inner neuroblastic
fibrous layer becomes the
nerve fiber layer
optic nerve forms in the
optic stalk
axons from the ganglion cells grow into the
optic stalk (starts 6th week and reach the brain by the 7th week)
inner cells in the optic stalk are:
mesoderm
outer cells in optic stalk are
glial cells that myelinated fibers
connective tissue sheath becomes the dura by week
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