Induced pluripotent stem $($iPS$)$ cells $$

$q,$

$$ requite a supply of donor egs cells, as is the case for embryonic stem cells.

$$ can difierentitate into any cell type from any species.

require a continual supply of fresh differentiation factors or they soon revert to the cell type from which they were originally derived.

can be created from most somatic cell types, including cells derived from adult tissues, by inducing expression of genes for a few key transcription regulators.

produce only short$-$lived differentiated cells. Therefore, many more iPS cells are needed to maintain a tissue than if ordinary stem cells were used.