WEEK 5- CP pt 2 Flashcards
how long doe sthe embryonic period last
day 1 to gestational week 8
in the embryonic period what is cell division called
cleavage
true or false in the embryonic period the zygote goes trhoygh many cell dividions
true
what is a zygote
a fertilized egg
when the zygote undergoes cell divisions that it is made up of 16 cells what is it called
MORULA
after many cell divisions when the xygot becomes a ball of cells what is it called
blastocyst
what day does the morula become the blastocyst
day 5
on day 6 the blastocyst has two mass cells what are tehy
inner mass cell embryoblast
outer mass cell trophoblast
on day 7 what two layers does the trophoblast split into
synctiotrophoblast and cytotrophoblast
what is teh function of synctiotrophoblast
to help the blastocyst errode the epithelium of the uterus= to make it easier to enter
on day 8 embryoblast turns into the epiblast and hypoblast, together whta is this called
bilaminar germ disc
on day 9 the blastocyst enters where
endometrium
when the blastocyst enter the endometrium it has two cavities, what are they?
yolk sac
amniotic cavity
the yolk sac faces what
the hypoblast
the amniotic cavity faces what
the epiblast
By the second gestational week what do we have
Bilaminar germinal disc
amniotic cavity
yolk sac
what two layers make up the bilaminar germinal disc
epiblast
hypoblast
what is the epiblast
layer of columnar cells adjacent to the amniotic cavity
what is the hypoblast
layer of cuboidal cells facing the yolk sac
in addiitnal to the bilaminar germinal disc what else do we have at the second week
amniotic cavity and yolk sac
what is the amniotic cavity
protection of embryo/fetus
what is the yolk sac
Early site of blood cell formation
true or false at the end of week 3, the he Blastocyst penetrates the superficial (Compact) layer of the endometrium of the uterus= complete implantation
false weel 2
week 3 is called what
gastrulation
what soecifically happens to the bilaminar germ disc as of week 3
it becomes the trilaminar germ disc
In the 3rd week (gastrulation) what cells undergo differentiation
inner mass cells (epiblast and hypoblast)
in gastrulation period, what happens to epiblast cells
they migrate into the midline
in gastrulation period, what do epiblast cells form onece theyve reached midline
PRIMITIVE STREAK
what is a primitive streak
streak that elongates caudal to cranial
in the gastrulation period what do some epiblast cells do after migrating to form the primitive streak
they enter the hypoblast
what happens when the epiblast cells enter the hypoblast?
they transform hypoblast into endoderm
what happens to the remaining epiblast cells that do not merge with hypoblast
they differentiate to become ECTODERM
the epiblast cells that are between hypoblast and epiblast form what layer
the mesoderm
true or false in gastrulation the notochord is made up of firstly the endoderm (inner layer)
flase its starts off as mesodermal tirssue
true or false, once the epiblast merges with hypoblast and becomes endoderm there is no more hypoblast layer
true
which two layers does the mesorderm remain
between the ofrmer layers of bilaminar disc
ectoderm is derived from
epiblast cells
in gastrulation what happens to each layer (endoderm, mesoderm, ectoderm)
they differentiate into different types of cells
the endoderm gives rise to whch cells
lung
thyroid
digestovce
true or false the endoderm is the oute rlayer
flase= innder
the mseoderm gives rise to which specific cells
cardia
skeletal
kidney
rbc
smooth muscle
the ectoderm gives rise to which specific cells
skin cells of epidemris
neurons of brain
pigment cells
true or false the mesoderm is the middle layer
true
true or false the ectoderm is the layer that forms our cns
true
the ectoderm is the ______ layer
outer
the notochord originates fromw hat structure
mesoderm
true or false the notocord is temporary stcuture
true
what are the functions of notochord
- Axis for symmetry
- Sends inductive signals that causes cells in the ectoderm to become neuroectodermal precursor cells >- neural plate
The lateral edges of the _______ become more elevated and will form the neural crest
ectoderm
which layer forms the neural crest
ectoderm
the depressed. mid region is called
neurla groove
the neural groove is a
depressed mid region beteern the neural crests
once we have the neural crest and neural grrove what is this layer caleld
neural plate
norectodermal cells give rise to
neural plate
the neural tube is derived from what
the neural plate
the neural tube becomes what
the brain and spinal cord
neural crest cells give rise to
sensory and autonomic ganglia
Neuralstemcellsthat produce ….
precursor cells
thw two sides of neural crests meet eachother to form
neural tube
what are somite
comes from mesoderm
important function that gives rise to vertebra
what does vertebra arise form
somite (mesoderm)
what is neurulation
formation of neural tube
when the neural tube closes the embryo forms ehat
the 3 primary vessicles
what are the 3 primary vessicles
procencephalon
mesencephalon
rhombencephalon
procencephalon gives rise to which brain
forebrain
the mesencephaloln gives rise to which brain
midbrain
the rhobencephalon gives rise to which brain
hindbrain
true or false the mesensephalon subdivides
false
the prosencephalon divides into
telencephalon
diencephalon
the rhombemncephalon divides into
metencephalon
myencephalon
telencephalon forms
cerbreal hemisphere
diencephalon forms
hypothalamus and thalamus
mesencephalon forms
midbrain
metencephalon forms
pons and cerebellum
myencephallon forms
medulla
is caudal closer to the head or feet
feet
cranial points in the direction of…
the head
true or false the synctioblast is on the outermost layer
true
fetal period is from what week to …
9 - delivery
what important stuff happen in the 9th week
neuron production migration and differentiation
formation of gyri and sulci !!!
true or false the brain wrinkles caudal to rostral
false
true or false the brain wrinkles rostral to caudal
true
true or false the brain stays teh same size throughout the entire fetal period
false, increases in size
what weel is formation of gyri and su;lci completed
week 37
around what day are the vessicles differentitaed
day 49
what happens from the end of gastrulation to day 42
Increase number of neural progenitor cells (mitotic) (symmetrical).
what happens after day 42
process becomes asymmetrical, meaning that the progenitor cells divide into one neural progenitor and one neuron.
true or false Most neurons are produced in the ventricular zone and migrate outwards.
true
gastrulation is between what days
14-21
neurulation is when (in weeks)
between week 3 and 4
what are the two types of neural tube migration
radial migration
tangental migration
in which direction doe sthe neural tube move in radial migration
out
in which direction doe sthe neural tube move in tangential migration
up
what are the two METHODS of migration
Somal translocation:
glial mediated migartionn
what is somal tarsnlocation and which kinds of migration do we see
the cell bodies move up and out to reach to target nad destination
what glial mediated migration and which kinds of migration do we see
cell moves along a radial glial network
moved OUT = deepest layer to surface
what two layers dissapear at the end of the fetal period
Themarginalzoneand subplate
in the mature barin how many cortical layers do we have
6
neurons develop what
axons and dendrites
in the cns axons are myelanted with what glial cell
oligodendrocytes
true or false post natally we still have alot of neurogeneis
false, a bit but not alot
when does neuron production occur
afyer day 40
NAME THE PHASES WEVE LEARNT AND THEIR TIMELINE
day 0 fertilization
day - 5morula becomes blastocyst
day 9 blastocyst implants itself in uterine wall
in second week (days 8-14) : we have the epiblast, hypoblast, –> we have bilaminar disc aniotic cavity and yolk sac
in 3rd week (14-21) is where gastrulation occurs (where epiblast and hypoblast differentiate in layers and becomes trilaminar disk)
from end pf gastrulation to day 42 = neurons develp in symmetrical way
neurulation ahppens from week 3-4 (day 21- 28) –> where neural tube is formed induced by notochord
after day 42 (week 6) neurons start to divide in more assymetric manner
embryonic period ends at week 8
week 9- fetal period
sulci and gyri start forming and finish at week 37
