LIFE SCIENCE

Detailed explanation-1: -Opponents argue that the research is unethical, because deriving the stem cells destroys the blastocyst, an unimplanted human embryo at the sixth to eighth day of development. As Bush declared when he vetoed last year’s stem cell bill, the federal government should not support “the taking of innocent human life.”

Detailed explanation-2: -Embryonic stem cells-the most controversial type-are taken from a blastocyst, an embryo at an early stage of development and comprising around 120 undifferentiated stem cells. These cells are called “totipotent” because they can differentiate into any cell type, including other totipotent cells.

Detailed explanation-3: -Current ethical controversies regarding stem cell-based therapy are focused on the unlimited differentiation potential of iPSCs which can be used in human cloning, as a risk for generation of human embryos and human-animal chimeras.