Northwestern University Feinberg School of Medicine

Center for Genetic Medicine

Transgenic Projects

Transgenic mice produced by the TTML are generated by the microinjection of purified DNA into the male pronucleus of single-cell fertilized mouse embryos (zygotes). Microinjected embryos are then surgically transferred into the reproductive tract of a pseudopregnant female who carries the pregnancy to term.

Transgenic DNA integrates randomly into the embryonic genome following microinjection. Usually, multiple copies of the transgene integrate at a single chromosomal site just prior to the first cell division, which ensures that the transgene is present in all nucleated cells of the developing embryo. Approximately 10-30% of the microinjected embryos that develop to term will inherit the transgene. These founder (F0) mice, although carrying the same transgene, are unique as they vary from each other in the number of transgenes that integrate (transgene copy number) and the chromosomal site at which the transgenes integrated (integration site). Both the integration site and, to a lesser extent, the transgene copy number can affect transgene expression patterns, which must be determined for each newly created line.

Frequently Asked Questions