lectures - mammalian hypoblast/Visceral endoderm formation

what is the general purpose of the hypoblast

prepare embryo for explosion of cellular compelxity

in mammals after epiblast and primitive endoderm progenitor cells are made, what happens to them

they undergo differentiation and express different proteins and physically separate into layers of epiblast and PE

in mammals how do epiblast and PE progenitor cells separate

epiblast is more dorsal while PE is more ventral

in mammals where is the blastocoel at this stage of mammalian hypoblast/Visceral endoderm formation

between PE/hypoblast and epiblast

in mammals what occurs at the same time as PE/epiblast cell separation

elongation

in mammals what happens to the hypoblast/primitive endoderm during elongation

hypoblast/PE cells rapidly prolif and spread around blastocyst to line the open chamber and become the yolk sac endoderm

layer right below epiblast diff and det into hypoblast

in mammals what are the cells of the yolk sac endoderm

PE/hypoblast cells that line the yolk sac

once the PE/hypoblast cells spread out, what happens with the blastocoel in mammals

blastocoel is now bifurcated, composed of true blastocoel and yolk sac

describe the potency of the mammalian hypoblast cells when the yolk sac endoderm is created

lost pluripotent, now multipotent

when is the mammalian yolk sac formed

during elongation

what happens to the mammalian epiblast cells during elongation

the epiblast undergoes cavitation to create the amnion and amniotic cavity

which mammalian PE cells become hypoblast rather than yolk sac endoderm

the remaining PE cells against the blastocoel undergo determination and differentiation to form hypoblast

what is the function of the mammalian amnion

to make amniotic fluid and line the cavity

no contribution to embryo proper

of the differentiated epiblast cells, which cells form the amnion in mammals

proximal cell lineage (prox to maternal body)

of the differentiated epiblast cells, which cells form the epiblast in mammals

distal cell lineage (distal to maternal both)

what is the special extra function of mammalian layer formation

the establishment of anterior-posterior axis occurs here

describe the start of the establishment of anterior-posterior axis in mammals

starts with continued prolif in amnion, epiblast, and PE cells

+ det and diff of PE cells

what does the mammalian PE split to form

splits to form visceral endoderm/hypoblast and the yolk sac endoderm

what are the mammalian visceral endoderm cells

PE cells adjacent to epiblast in mice

during ant-post axis formation, what happens with VE in mammals

at the most distal point, VE activates by extracellular env. causing det to express genes making region different → distal visceral endoderm DVE

what is the function of the DVE in mammals

to migrate up one side of the blastocyst via massive prolif + diff + det and become the anterior visceral endoderm AVE

what is the function of the AVE in mammals

it signals to become the anterior of the embryo

in mammals, anything not sending signals to become anterior

doesn't become anterior

what does the mammalian hypoblast/VE do and not do

does form from PE

does not contribute to embryo or extra-embryonic mems.

what is the mammalian blastula formed of

epiblast + hypoblast/VE

mammalian blastula is...

bilaminar

what does bilaminar mean

2 true layers

PE becomes

hypoblast/VE + YSE