Stem Cells

Stem Cells

Intro

• In a multicellular organ, most cells are specialised
• However some cells remain unspecialised, these are called stem cells
• Stem cells are undifferentiatied, can keep dividing and can give rise to other cell types.

Development

• Soon after fertilisation a zygote divides repeatedly
• These early cells are ALL stem cells, embryonic stem cells
• Theses stem cells can develop into any of the 216 cell types, they are totipotent. 
• As the embryo develops many stem cells remain, these are called pluriptent. They are able to divide into any type of cell but not the cells of the placenta.
• In adults, some cells retain this ability. They can give rise to a limited number of body tissues, multipotent stem cells.

Sources

• Main source of embryonic stem cells are from unused embryos from IVF
• Adult stem cells are found in the bone marrow
• Therapeutic cloning takes the nucleus from an ovum and…