Differentiation

Differentiation is the process during development whereby newly formed cells become more specialised and distinct from one another as they mature

All cells of an organism share an identical genome – each cell contains the entire set of genetic instructions for that organism

The activation of different instructions (genes) within a given cell by chemical signals will cause it to differentiate

When a cell differentiates and becomes specialised, it loses its capacity to form alternative cell types

Stem cells are unspecialised cells that have two key qualities:

1. Self Renewal – They can continuously divide and replicate

2. Potency – They have the capacity to differentiate into specialised cell types

Types of Stem Cells

There are four main types of stem cells present at various stages of human development:

Totipotent – Can form any cell type, as well as extra-embryonic (placental) tissue (e.g. zygote)

Pluripotent – Can form any cell type (e.g. embryonic stem cells)

Multipotent – Can differentiate into a number of closely related cell types (e.g. haematopoeitic adult stem cells)

Unipotent – Can not differentiate, but are capable of self renewal (e.g. progenitor cells, muscle stem cells)

Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a new-born baby and from an adult’s own tissues

ANIMATIONS