third week Flashcards
(31 cards)
what is the primitive streak and how long (day?)
a groove on de mid sagital plane of the embryonic disc. (day 15-16) 50% of the embryonic disc length
What body axes does the primitive streak define?
caudal-cranial axis
medial-lateral axis
left right axis
the dorsal ventral axis of the primitive streak is equavilant to?
ectoderm-endoterm axis
what happens during gastrulation?
epiblast cells move toward primitive streak, enter the primitve streak and then migrate away from the primitve streak as individual cells.
what is ingression
the movement of cells through the primitve streaj and into the interior of the embryo
epithelial-to-mesenchymal transformation (EMT) , what cells and where
epiblast cells that migrated in the primitve streak. where they undergo epithelial-to-mesenchymal transformation (EMT)
what does a epithelium mostly consits of
a sheet of regurly shaped cells (cuboidal) tighly interconnected lateral
what does a mesenchyme consist of?
irregular shaped loosely connected cells
what happens to the shape of epiblasts during EMT?
the elongate and become flask shaped.
how do they detach from their neighbors? structure of (pseudopdia filopdia lamellipodia) and function
they extend footlike processes called pseudopdia
filopdia (thinner)
lamellipodia (flattended)
help migrate through p. streak
what is gastrulation
bilaminar to three primary germ layers.
what happens to the hypoblast during gastrulation
they are bering displaced by epiblast cells, so that they are replaced by the definitive endoderm
to what does the definitive endoderm give rise in the future?
lining of the gut and to gut derivatives.
what are the four main subdivisions of the intraembryonic mesodern
cardiogenic mesoderm, paraxial mesoderm, intermediate mesoderm, lateral plate mesoderm
what is the notochordal process
a population of mesodermal cells that migrate cranially from the primitive node at the midline to form a thick walled midline tube.
what is the oropharyngeal membrane?
cranial membrane
what is the cloacal membrane
cadual membrane
what does the oropharyngeal membrane become?
the opening of the oral cavity
what does the cloacal membrane form?
opeing of the anus and urinary, genitalia tract
what does the ectoderm differentatie into
neural plate and the peripheral surface ectoderm
how does the embryo develop from what side to what side
cranial to caudial
so first ingression will stop cranially because nof epiblasts are present
what does the trilaminar disc consist of?
ectoderm, mesoderm and definitive endoderm
where are all three germ layers derived of?
epiblast
what is organogenesis?
formation of organ rudiments and transformation of organ rudiments into organ systems
