Topic.2.Development.powerpoint.2.2.Later.development

Question 1

Gastrulation involves changes in :

Answer 1

cell motility
cell shape
cell adhesion

Question 2

What are some gastrulation movements we see?

Answer 2

Invagination
Ingression
Involution
epiboly
intercalation
convergent extension

Question 3

What is invagination and how does it relate to sea urchins?

Answer 3

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

Question 4

What is ingression and how does it relate to sea urchins?

Answer 4

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

Question 5

What is involution?

Answer 5

an epithelial sheet rolls inward to form an
underlying layer

Question 6

Epiboly

Answer 6

Epiboly: a sheet of cells spreads by thinning

Question 7

Intercalation:

Answer 7

rows of cells move between one
another, creating an array of cells that is longer
(in one or more dimensions) but thinner.

Question 8

Convergent Extension

Answer 8

rows of cells intercalate,
but the intercalation is highly directional.

Question 9

What is a defined feature that starts to form at the beginning of human gastrulation?

Answer 9

primitive streak, distinguishes A/P axis

Question 10

Primitive streak, which is analogous
to?

Answer 10

the blastopore of Xenopus(frog)

Question 11

Organogenesis is _

Answer 11

the process of formation of organs from three germ layers.

Question 12

Neurulation is a type of organogenesis. It’s_

Answer 12

the process of the neural tube formation(forms early brain and spine)

Question 13

Explain the process of neurulation

Answer 13

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)

Question 14

What induces the formation of the neural plate?

Answer 14

Ectoderm is induced to thicken and
form the neural plate by
signals from the mesoderm and
other surrounding cells

Question 15

Primary neurulation:

Answer 15

the neural plate creases inward
until the edges come in contact and fuse.

Question 16

Secondary neurulation:

Answer 16

the tube forms by hollowing
out of the interior of a solid precursor.

Question 17

Neural tube closes:

Answer 17

24-26 days

Question 18

In the neurulation,
what is the interior that is hollowed out and where does it go?

Answer 18

Neural crest cells migrate
to other parts of the embryo;
become many tissues

Question 19

Somites:

Answer 19

formed from mesoderm;
Give rise to vertebrae

Question 20

T/F: Notochord disappears entirely

Answer 20

notochord disappears before
birth, but parts of it become the
inner portion of vertebral disks in
adult

Question 21

How does cell differentiation come into play during neurulation?

Answer 21

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