Which technique collects the embryonic stem cells that line the inside of a developing blastocyst to produce embryonic stem cell lines?

Which technique collects the embryonic stem cells that line the inside of a developing blastocyst to produce embryonic stem cell lines?

• A. Pronuclear injection
• B. Genotyping
• C. Homologous recombination
• D. None of the above

Answer: (C)

The method for producing embryonic stem cell lines starts with isolating the inner cell mass that lines the blastocyst and then culturing those cells to establish ES cell lines. This isolation step is the actual way ES cells are collected, typically done by carefully dissecting the inner cell mass or using methods that separate those cells from the surrounding trophoblast. Pronuclear injection involves delivering genetic material into a fertilized egg to create transgenic animals, so it does not describe deriving ES cells. Genotyping is simply identifying the genetic makeup of cells or organisms, not deriving new ES cell lines. Homologous recombination, on the other hand, is a genetic engineering technique used to make precise changes within the genome of cells once ES cell lines have been established (for example, to knock out or modify a gene). It is a modification step applied after derivation, not the collection method itself. Therefore, the correct concept for how ES cell lines are produced points to the derivation from the inner cell mass, and the technique listed that actually modifies lines after they’re collected is homologous recombination. If you’re choosing from the options as written, none of them describe the collection process directly; homologous recombination is relevant for targeted genetic changes after derivation rather than the collection of ES cells.

The method for producing embryonic stem cell lines starts with isolating the inner cell mass that lines the blastocyst and then culturing those cells to establish ES cell lines. This isolation step is the actual way ES cells are collected, typically done by carefully dissecting the inner cell mass or using methods that separate those cells from the surrounding trophoblast. Pronuclear injection involves delivering genetic material into a fertilized egg to create transgenic animals, so it does not describe deriving ES cells. Genotyping is simply identifying the genetic makeup of cells or organisms, not deriving new ES cell lines. Homologous recombination, on the other hand, is a genetic engineering technique used to make precise changes within the genome of cells once ES cell lines have been established (for example, to knock out or modify a gene). It is a modification step applied after derivation, not the collection method itself. Therefore, the correct concept for how ES cell lines are produced points to the derivation from the inner cell mass, and the technique listed that actually modifies lines after they’re collected is homologous recombination. If you’re choosing from the options as written, none of them describe the collection process directly; homologous recombination is relevant for targeted genetic changes after derivation rather than the collection of ES cells.