Question

what's the relation between teratomas and ES cells, and the experiments to show their similarity

Answer 1

Teratomas are cancerous cells which undergo uncontrolled cellular division. Similarly, the ES or embryonic stem cells are pluripotent stem cells which have the capability of going very intensive cell growth as compared to normal cells. Similar to teratomas, the ES cells are also capable of underoging change in phenotype depending upon the proximity of different types of cells and/or appropriate signal/chemical/stimulus. Further, the telomerase activity of both these cell types are very high thus self-renewal of the chromosome takes place very frequently. Finally, many molecular pathways are held common between these two cell types, thus giving them a very similar signature of signalling events.

Thus, the teratomas and the ES cells have very similarities to each other and hence, uncontrolled cellular division in the ES often lead to teratomas/cancer in organisms. Genetic screening and cell-growth experiments often show these similarities.