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DEVBIO LE1
04 Cleavage to Blastulation
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Cards (39)
developmental properties of cleaving embryos
-
regulative
development
-
totipotent
at the end of blastula mammalian has
2
distinct
populations of
cells
at the end of blastula avian has
stack of cell
layers
at the end of blastula amphibian has
ball
of
cells
translucent area in avian embryo
area
pellucida
area that appears dark in avian embryo
area
opaca
what layer is formed when cells on top of the avian embryo fall off
hypoblast
what cavity is formed when cells on top of the avian embryo fall off
subgerminal
cavity
the first plane of cleavage in the avian involves
blastodisc
what type of cleavage does mammalian have
holoblastic
rotational
what type of cleavage does frog
have
holoblastic
radial
three distinct regions recognized after blastula
-
gray
crescent
-
vegetal
region
-
animal
region
late cleavage to blastula transition
morula
how many cells does the embryo have when a cavity is formed
128
formed due to cortical reaction where there is mass movement of pigment towards sperm entry
gray
crescent
telolecithal cleavage pattern
meroblastic
- isolecithal and mesolecithal
- complete
- proceeds from animal hemisphere going down to vegetal hemisphere
holoblastic
- concentration of yolk at the center of the oocyte
centrolecithal
- dense amount of yolk
- heavily concentrated on one pole
telolecithal
- moderate amount of yolk
- slightly concentrated on one pole
mesolecithal
- small amount of yolk
- evenly distributed
isolecithal
factors influencing cleavage pattern
-
maternal
cytoplasmic
factors
-
amount
and
distribution
of
yolk
site of first cleavage furroe
angle
of
mitotic
spindle
what is required for the cell to grow
new
players
/
regulators
and
addition
of
gap
phases
what controls the cell cycle
m
phase
promoting
factor
what stage has the characteristic of a mature cell cycle
late
embryonic
cell
when embryo stops dividing, it results in
-
zygotic
genome
activation
-
synchronous
cell
division
is
lost
what happens when maternal derived cyclin b and cell cycle factors deplete
switch
to
zygotic
transcription
what is the source of mpf in the embryo
cyclin
b
protein involved in spindle fiber organization
regulatory
cytoplasmic
proteins
protein involved in nuclear membrane depolarization, breakdown and degradation of nuclear membrane
nuclear
membrane
proteins
proteins involved in chromatin condensation and become distinct chromosomes
histone
enzyme that phosphorylates a target protein inside the cell
cyclin
b-cdc2
complex
what happens with kinase during s phase
it gets
synthesized
and forms a
complex
with
cdc2
and gets
reactivated
what inactivates the kinase
breakdown
of
cyclin
b during
mitosis
2 subunits of MPF
cyclin b
and
cdc2/cdk1
fuel molecule for the transition from zygote to cleavage stage
mitosis promoting factor
when does cell division slow down?
when a
balance
or
set point
is attained
what are the characteristics of cleavage
- generates
large
number of
cells
- generates many
copies
of the
zygotic genome
-
segregates cytoplasmic components
into different
blastomeres
-
increases
the
ratio
of
nuclear volume
:
cytoplasmic volume