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BMS247 Stem Cells > L2 - Germ Cells > Flashcards

L2 - Germ Cells Flashcards

1
Q

What is seen during development in terms of potency and specialisation

A

See a gradual restriction in potency of multipotent cells to specialised comitted cell fates

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2
Q

Cells initially are

A

Totipotent

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3
Q

Define pluripotent

A

Able to form all of the tissues of the body except the placenta `

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4
Q

Describe what happens in the first 3 weeks post fertilisation

A

Body axes are gradually established

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5
Q

What type of cells are set aside for the next generation

A

Gonadal germ cells

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6
Q

In many animals there is an early division between __________ and ________ cells

A

Somatic and germ

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7
Q

What is interesting RE somatic cells in plants

A

Are able to form new organims

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8
Q

Where are the primordial germ cells determined

A

In a specific location on the edge or outside of the developing embryo

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9
Q

PGCS

A

Primordial germ cells

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10
Q

Where do PGCs migrate to

What do they become here

A

Migrate to the gonad

Become the progenitor population for eggs and sperm

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11
Q

What do you need (2) for the determination of the germ cells

A

Totipotent (plastic) cells

Cell which is capable of underogoing meiosis

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12
Q

Describe how the nematode worm gave us conceptual understanding about the formation of germ cells

A

Nematode worm has a specfic no cells (lineage can be traced)

Early assymetric divsions leads to the formation of the P lineage

This cell makes its way to the posterior of the cell

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13
Q

Describe how asymmetric cell division takes place

A

Coupling the polarisation of the cytoplasmic determinants to the oriented plane of cell division

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14
Q

What does the P cells act as

A

Pre germ cell

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15
Q

Throughout asymm divisions what to the P cells inherit

Describe their composition

A

P-granules

Mix of protein and RNAs

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16
Q

Describe how the P-granuel work

A

Binds to the DNA of the P cell and block alsmost all transcription and differentiation

Block translation in the cytoplasm

Promote stem cell fate and stimulate meiosis

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17
Q

Describe what is seen when Nem worm P cells are stained for transcriptional

A

There is no transcriptional act

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18
Q

Similar P-cell exist in vertebrates

Where are they found

A

Always at the posterior

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19
Q

Germ line established which shows:

A

Little transcription and translation –> no differentiation

Able to undergo meiosis

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20
Q

What mechanisms are involved in the shutting down of PGCs

A

Epigenetic silencing

Histone modifications (methylation and deacetylation)
DNA methylation
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21
Q

PGCS arised from __________________

A

Extra-embryonic mesodendodermal cells

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22
Q

Where do PGCS stay during axes formation

What is the reaosning behind this

A

Beyond the posterior part of the embryo

Protected form signals which are specifying the body axes

23
Q

Why are PGCs pluripotent

A

Because genes that code for differentiation factors are repressed transcriptionally and translationally

24
Q

When to PGCs migrate

A

Once rapid differentiation of embryogenesis begins to decrease

25
Q

Describe the migration of the germ cells

A

Passively ride the endoderm - attaches to endoderm to migrate through the midgut then attaches to the mesoderm

26
Q

Where is the final destination of the PGCs

A

Gonadal niche

27
Q

In the ovaries cells attach to the

A

Stromal caps

28
Q

In the testes the cells attache to

A

Hub cells

29
Q

Describe the migration of the PGCs in chick/mouse/human

A

Migrate throguh the posterior (hindgut) along a fibronectin rich trail

Then leave the gut to move more laterally to the genital ridges

30
Q

What is the function of the gonadal niche

A

Provision of a specialist microenvironment which protects the PGCS in their pluripotent state

31
Q

Descrive the travelling stem cell niche idea

A

Support cells travel with PGCs secreting SCF to maintain the undiffernetiated cell type

32
Q

What is SCF

A

Stem cell factor

33
Q

What is the affect of a mutation which means SCF is unable to be produced

A

Stem cells are no longer protected and would differnetiate

34
Q

What is the affect of a mutation which means that the chemoattractant is no longer produced

A

Would get stuck in the gut and would fail to make it to the niche

35
Q

Describe how PGCS can lead to formation of teratomas

A

Failure to migrate to the protective niche would lead to the formation of teratomas

36
Q

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

A

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

37
Q

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

A

Inner cell mass

38
Q

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

A

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

39
Q

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

A

Inner cell mass

40
Q

Define a stem cell

A

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

41
Q

How is a progenitor cell different to a stem cell

A

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

42
Q

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

A

Adult stem cells or tissue specific stem cells

43
Q

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

A

T

44
Q

Describe the potency of adult stem cells

A

Multipotent or pluripotent

45
Q

What is meant by cellular homeostasis

A

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.

46
Q

Give an example of where cellular homeostasis changes during life

A

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

47
Q

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

A

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

48
Q

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

A

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

49
Q

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

A

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

50
Q

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

A

Umbilical cord and placental tissue

51
Q

Stem cells respond to physiological signals, T or F

A

T

52
Q

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

A

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

53
Q

In which three regions are neural stem cells found

A

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

54
Q

What is the other name of neural stem cells

A

Neural precursor cells

BMS247 Stem Cells (14 decks)

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