2.4: Tissue Morphogenesis Flashcards
define development
organism growth and change
t/f is multicellular development an ongoing process (even in adults)
true, it still occurs in adults from stem cells + even completely new developmental processes can also be initiated in adults aka pregnancy
which layer of the skin can be dubbed the stem cells on the skin and which are the connective tissue and epithelial of the skin
basal-cell layer is the stem cells. dermis is connective tissue and epithelial is epidermis
describe the steps on how to get from egg to blastula, to gastrula in multicellular development during embryogenesis
fertilized egg –cleavage–> blastula –gastrulation–> gastrula
*gastrulation if the formation of the gut tube
state the 3 key steps in the outline of multicellular development and morphogenesis
- cell proliferation
- cell differentiation
- morphogenesis
define morphogenesis and the 3 steps (+ their components)
morphogenesis = generation of shape
1. cell internationalization: ingression/delamination, invagination/involution
2. elongation: convergent extension, cell growth/cell division/and cell matrix deposition
3. fine repositioning of cells: migration of whole cells and migration of a cell extension
which 3 key tissue layers are formed during gastrulation (morphogenesis)
ectoderm (epidermis and nervous system), mesoderm (muscles, connective tissue, bones, blood, kidneys, etc), endoderm (gut, lungs, pancreas, liver, etc)
define gastrulation
change from ball of cells to embryo with a gut and 3 germ layers (ectoderm, mesoderm, endoderm)
how is the mesoderm formed from the blastomeres in gastrulation
cell internalization by ingression (moving inwards)/delamination (forming into layers)
the ectoderm, mesoderm, and endoderm are made from which types of cells
blastomeres (ecto are the cells that stay put, meso are the ones crawling around the inner surface, endo is the indented lining)
explain the ingression and delamination processes in gastrulation
ingression: individual cells detach from the outer cell layer and migrate in (this is an epithelial to mesenchymal transition)
*mesenchymal is the loose, undifferentiated, connective tissue
delamination: these cells form a new layer = mesoderm
t/f do epithelial to mesenchymal transition need to be carefully controlled
true - they might become cancer
describe the process of how the endoderm arises from blastomeres through gastrulation
cell internalization by invagination (making cavity/pouch)/involution (curling inward) form the endoderm. attached cells in an epithelial cell sheet are pulled into the middle of the embryo while remaining attached (invagination) and these cells curl in and grow (involution) to form the endoderm.
invagination of epithelial sheet is caused by what
caused by a organized tightening along adhesion belts in selected regions of cell sheets
the vertebrate neural tube forms via which processes
invagination/involution
explain the formation of the vertebrate neural tube
- the vertebrate neural tube forms via invagination/involution.
- upstream developmental signals instruct specific cells to differentiate from ectoderm to neural plate cells
- neural crest plate invaginate to form the neural tube
- instructions include differential gene expression (eg different cadherins)
regarding vertebrate neural tube, the neural tube becomes what ? and the neural crest tails becomes ?
the neural tube becomes brain or spinal cord and the neural crest tails becomes peripheral nervous system
Which of the following statements made by (imaginary) BIO230 students is
not true?
a) “Formation of the neural tube uses invagination, but formation of the gut
tube does not.”
b) “Tissues with high cellular turnover typically also have molecular
turnover.”
c) “Some cells do differentiate in adults.”
d) “Development occurs throughout all phases of life, including during
adulthood.”
A.
It does, the part where it says “does not” is wrong
state the 2 steps of convergent extension
- cell converge (pile up in the middle), or crawl together
- cells extend of form a line (from the pile)
list how elongation can occur
convergent extension, mass cell migration, cell growth, division, matrix deposition, directional expansion
*cell growth, division, matrix deposition must be asymmetric
describe how mass cell migration can lead to elongation
cells can move as individuals or as a group to form different shapes, called collective cell migration.
chain type migration involves cell adherent cells (not stuck together)
sheet type migration involved more adherent cells
cluster cells are the in between form
what are the 3 forms of mass cell migration and what process does it lead to
- chain
- cluster
- sheet
they lead to elongation
what condition must be met for cell elongation to occur from cell growth, division, matrix deposition
the processes must be asymmetric
state the process of how plant cells often grow
directional expansion
describe how plant cells grow
they grow through directional expansion. the cell wall is an ecm made of polysaccharides - cellulose (a polysacc( can be asymmetrically distributed in the plane cell wall. cellulose constricts plan cell expansion forcing expansion in one direction = elongation. the plant cell wall seposition is guided by microtubules (uses udp gluc as energy_
depending on _________, it affects the alignment of cellulose synthase complex which makes many cellulose molecules and assembles them into a micrfibril
microtubules
disorganized _________ will disrupt plan cell elongation
microtubules
describe disorganized vs organized microtubules in plant cell organization
disorganized microtubules (=disorganized cellulose) will disrupt plan cell elongation by having no directional elongation and just lead to cell swelling. organized microtubles (organized cellulose) leads to turgor pressure and directional elongation
cerebral cortex cells (outer layer of brain made of many layers) are repositioned by ___________________
whole cell migrations - the first born neurons (older) are deeper in and newer ones at the surface)
describe the repoisitioning of cerebral cortex cells
cerebral cortex cells are repositioned by whole cell migrations. whole cells migrate to the tip of the radial glial cells; the neurons from the dividing progenitor cell run up the radial glial cell to the top layer. first born neurons are in the deeper layer and last born are in eh outer layer.
______ are positioned by migration of cell extension - attractants direct the extensions of the growth cone in a particular direction
axons
what directs the extensions of the growth cone in a particular direction in regards to neural growth
attractants (similar to rac rho signalling for neutrophils but with diff specifics)
Which morphogenesis process is correctly matched with the example
developmental process?
a) Cell division & cell shape change – neural tube formation
b) Convergent extension – plant cell elongation
c) Ingression/delamination – cerebral cortex development
d) Invagination/involution – gastrulation
D.
A is wrong bc its invagination/involution. B is wrong bc it’s directional expansion (like slinky). C is wrong bc it’s whole cell migrations.
