1. Early Embryonic Development
Stem Cells

2. Stem Cells – Part 1 The Information
What are they?
Where do we get them from?
Are they all the same?
Why are we interested in them?

3. How cells become specialised
Correct stimulus is given to unspecialised cells e.g. a chemical stimulus
Some genes are switched on and become active; other genes are switched off
m-RNA is made from the active genes
m-RNA moves to the ribosomes; the ribosomes read the m-RNA and the appropriate protein is made
The protein can permanently alter the structure and function of cells

4. Stem Cells – What are they?
A type of source or master cell that can . .
Undifferentiated cells
Which keep dividing
And can give rise to other cell types

5. Potency How much stem cells differentiate is called potency
Stem cells vary in their potency:
Totipotent: can give rise to any cell and so can produce a whole organism
Pluripotent: potential to develop into many cell types but not all of them.
Multipotent: cells retain the capacity to make a few types of cell
Unipotent: make one type of cell e.g. Skin cells

6. What are they and where are they found?

7. Timeline of development
Day 1: Fertilisation – a zygote is formed
Series of rapid cell divisions
No increase in size
Day 5: Blastocyst – a hollow ball of cells
Outer layer Placenta
Inner 50 cells Embryo
Week 12: Fully differentiated foetus.

8. Zygote: Totipotent stem cells
Blastocyst: Pluripotent stem cells
Foetus and adult: Mulitpotent and unipotent stem cells

9. Stem cells and their use in medicine
Sources of stem cells:
Multipotent cells from adults
Spare embryos from IVF
(pluripotent)
Umbilical cord stem cells
Therapeutic cloning or admixed embryos

13. Different view points

14. Just a last point....

15. Ethical considerations
Where do you stand on the issue of using embryonic stem cells?
What are the advantages and disadvantages of using them in research?