Topic.2.Development.powerpoint.2.2.Later.development Flashcards
Gastrulation involves changes in :
cell motility
cell shape
cell adhesion
What are some gastrulation movements we see?
Invagination
Ingression
Involution
epiboly
intercalation
convergent extension
What is invagination and how does it relate to sea urchins?
a sheet of cells (called an epithelial sheet)
bends inward
Ex: sea urchins the vegetal pole after some mesenchymal cells leave, invaginate to from archenteron
What is ingression and how does it relate to sea urchins?
individual cells leave an epithelial sheet and
become freely migrating mesenchyme cells.
Ex: In sea urchins, mesenchymal cells leave vegetal pole and migrate to the blastocoel to release calcium carbonate that forms skeletal system
What is involution?
an epithelial sheet rolls inward to form an
underlying layer
Epiboly
Epiboly: a sheet of cells spreads by thinning
Intercalation:
rows of cells move between one
another, creating an array of cells that is longer
(in one or more dimensions) but thinner.
Convergent Extension
rows of cells intercalate,
but the intercalation is highly directional.
What is a defined feature that starts to form at the beginning of human gastrulation?
primitive streak, distinguishes A/P axis
Primitive streak, which is analogous
to?
the blastopore of Xenopus(frog)
Organogenesis is _
the process of formation of organs from three germ layers.
Neurulation is a type of organogenesis. It’s_
the process of the neural tube formation(forms early brain and spine)
Explain the process of neurulation
18 days post fertilization, neural plate appears and invaginates along central axis to form neural groove with folds on each sides
The neural folds approach each other in
the midline and fuse there, thus converting the neural groove into a neural tube (around 20 days)
What induces the formation of the neural plate?
Ectoderm is induced to thicken and
form the neural plate by
signals from the mesoderm and
other surrounding cells
Primary neurulation:
the neural plate creases inward
until the edges come in contact and fuse.
Secondary neurulation:
the tube forms by hollowing
out of the interior of a solid precursor.
Neural tube closes:
24-26 days
In the neurulation,
what is the interior that is hollowed out and where does it go?
Neural crest cells migrate
to other parts of the embryo;
become many tissues
Somites:
formed from mesoderm;
Give rise to vertebrae
T/F: Notochord disappears entirely
notochord disappears before
birth, but parts of it become the
inner portion of vertebral disks in
adult
How does cell differentiation come into play during neurulation?
Cadherin expression:
Cadherins: transmembrane proteins that play an important role in cell adhesion
In neurulation: neural folds approach each other in the midline and fuse there, thus converting the neural groove into a neural tube
