Lecture 27

Question 1

What structure do cells at the periphery of the mammalian blastocyst form and from what fate is this

Answer 1

Cells on the outer periphery of a human/mammal embryo assume a different fate; the trophectoderm that forms the placenta

Question 2

What is the name given to the cells that occupy the inside of the trophoblast

Answer 2

Inner cell mass

Question 3

What is the significance of the cells inside the trophoblast not occupying the full space

Answer 3

The cells of the inner cell mass cluster at one side, the cells closest to the trophectoderm will give rise to the epiblast whereas the cells furthest from the trophectoderm will give rise to the hypoblast

Question 4

From which region of the human embryo are human ES cells found

Answer 4

Inner cell mass

Question 5

Define a stem cell

Answer 5

A cell capable of endless self-renewal and can give rise to a daughter that can give rise to several lineages

Question 6

How is a progenitor cell different to a stem cell

Answer 6

A progenitor cell is only capable of limited self-renewal as well as limited differentiation propensities

Question 7

What are the names given to the stem cells found in the mature tissues

Answer 7

Adult stem cells or tissue specific stem cells

Question 8

As development proceeds, most somatic cells become differentiated and not mitotic, T or F

Answer 8

T

Question 9

Describe the potency of adult stem cells

Answer 9

Multipotent or pluripotent

Question 10

What is meant by cellular homeostasis

Answer 10

Cellular homeostasis is the constant or periodic generation of new cells to replace old, damaged, and dying cells, or the addition of new cells as needed.

Question 11

Give an example of where cellular homeostasis changes during life

Answer 11

Pregnant females produce more red blood cells. RBCs are made continuously through life from haematopoietic stem cells in the bone marrow. Haematopoietic stem cells respond to increased levels of oestrogen found in pregnant females, to become hyper-activated and make many more daughter cells

Question 12

Adult regeneration/repair that occurs routinely in these tissues occurs via a very different mechanism to how they were first generated in the embryo, T or F

Answer 12

F - adult tissue regeneration/repair mirrors the way the cells form in the embryo

Question 13

What is meant by the niche in which tissue specific stem cells reside

Answer 13

complex microenvironments around the stem cells, made up of many cells, that interact with the environment and the stem cell to decide whether to activate it

Question 14

Haematopoietic stem cells give rise to all the blood cell types, what two classes of blood cells are these

Answer 14

Myeloid cells – monocytes, macrophages, neutrophils, basophils, eosinophils and erythrocytes as well as megakaryocytes/platelets and dendritic cells. Lymphoid cells – T, B and NK Cells

Question 15

Other than in the bone marrow, where else are HSCs found

Answer 15

Umbilical cord and placental tissue

Question 16

Stem cells respond to physiological signals, T or F

Answer 16

T

Question 17

What can the factors released by the adjacent cells of the HSC niche act to achieve

Answer 17

Regulate stem cell activity and the decision as to whether to remain quiescent, or become active. They can also trigger division to give another HSC or a daughter that will differentiate

Question 18

In which three regions are neural stem cells found

Answer 18

Subventricular zone lining the lateral ventricles, the subgranular zone and in the hypothalamus lining the 3rd ventricle

Question 19

What is the other name of neural stem cells

Answer 19

Neural precursor cells