Lecture 9: Stem Cell 2

Question 1

What are the two layers of mammalian skin?

Answer 1

1. Dermis
2. Epidermis

Question 2

How is damage to the dermis repaired?

Answer 2

Damage to the dermis is repaired by proliferation of fibroblasts that are present in the dermis, and the regrowth of blood vessels

Question 3

What do basal layer cells require to remain proliferative?

Answer 3

Stimulation from fibroblasts in the dermis, and extracellular signalling molecules from the basement membrane

Question 4

What is the stem cell niche for epidermal stem cells?

Answer 4

Basement membrane and dermis

Question 5

What is epidermolysis bullosa? and how does it occur?

Answer 5

Epidermolysis bullosa is a disease that occurs when the epidermis is not properly attached to the basement membrane and as a result, the epidermis is very fragile and blisters easily. This occurs when there is a mutation in the basal layer that expresses keratin type 5 and 14.

Question 6

What does the switch of keratin type 5 and 14 to 1 and 10 indicate?

Answer 6

The switch from keratin type 5 and 14 to 1 and 10 is a reliable indicator that cells have committed to terminal differentiation.

Question 7

Activation of _____ signalling in basal layer cells promotes differentiation

Answer 7

Notch

Question 8

_______ contribute to maintaining basal fate. Also, this factor, ______ produced by the dermis acts on basal layer cells to inhibit differentiation

Answer 8

Epidermal growth factor receptor (EGFR) and Wnt

Question 9

What is the stem cell niche for small intestine?

Answer 9

Paneth cells in the crypt and mesenchymal cells surrounding the crypt.

Question 10

What are satellite cells and how are they activated?

Answer 10

Satellite cells are a reserve of muscle stem cells. They become activated in response to muscle injury and they proliferate into myoblasts which then differentiate into new muscle fibres.

Question 11

How did/do satellite cells emerge?

Answer 11

Satellite cells emerge during the differentiation of skeletal muscle in the embryo and generate a potential reservoir of muscle tissue.

Question 12

How can satellite cells be recognized?

Answer 12

By their expression of characteristic protein CD34 and Pax7

Question 13

Where does neurogenesis occur?

Answer 13

In the sub-ventricular zone of the lateral ventricle and the sub granular zone in the hippocampus.

Question 14

___ signalling determines the number of stem cells and regulates ____ which promotes their survival.

Answer 14

Notch, Sonic hedgehog signalling (SHH)