Lecture 10: Morphogenesis 1

Question 1

Cellular forces control the process of morphogenesis in various ways. What are 5 mentioned in class?

Answer 1

1. Cell division
2. Change in cell shape
3. Rearrangement of cells w/n tissues
4. The development of hydrostatic pressure w/n structure
5. The migration of individual cells and group cells from one part of the embryo to another

Question 2

What are key properties of cells for morphogenesis? Explain in detail.

Answer 2

Cell adhesiveness (the tendency of cells to stick to one another and to their environment, interaction involves cell-adhesion molecules) cell shape (cell can actively change shape by means of internal connections and constrictions and by interaction with other cells), and cell migration (the ability of many type of cells to travel as individuals r groups from one location to another)

Question 3

Changes to cell adhesiveness is crucial to what?

Answer 3

To cell shape changes and to cell migration

Question 4

All cells have __________ at their membrane where they encounter extracellular environment

Answer 4

surface tension

Question 5

Adjacent cells in epithelia are joined together by what specialized structure?

Answer 5

Adherens junctions

Question 6

What are three classes of adhesive molecules that are particularly important in development? Which is the most important?

Answer 6

Cadherins, immunoglobulin superfamily and integrins. Cadherins is the most important

Question 7

Cadherins depend on ____ for their function

Answer 7

calcium

Question 8

How will cells with a large amount of cadherins segregate compared to cells with a lower amount of cadherins?

Answer 8

The cells with the larger amount of cadherins will serrate together and form sort of an epithelium whereas the cells with less cadherins will group together OUTSIDE (form a ring). Picture on slide 10

Question 9

The shape of cells in tissues are determined by counteracting forces. What are these forces?

Answer 9

1. adhesion between cells tend to increase the area of surface contact
2. contractile cytoskeleton limits the expansion of contacts

Question 10

What are the three principle types of protein polymers in the cytoskeleton?

Answer 10

actin filaments, microtubules, and intermediate filaments

Question 11

The change between epithelial cells and mesenchymal cells is known as what? What happens to the adherin junction? What is the organization of epithelial cells VS mesenchymal cells?

Answer 11

epithelial-to-mesenchymal transition. this change involves dissolution of the adherens junctions. epithelial cells are held tightly together by adherin junctions to form a continuous sheet. mesenchymal has a looser organization.