Direct microinjection of DNA into the pronucleus of a mouse zygote has been until recently the method most extensively used in the production of transgenic mice. If the foreign DNA integrates into the mouse chromosomal DNA at the one-cell stage, the animal will contain the injected DNA in every cell, including those of the germ line. If, however, integration occurs later, the resulting animals will be mosaic for the presence of the injected DNA.
Upon receipt of the DNA construct, proven by documentation to be of high quality and suitable for microinjection , we will proceed to inject 150-200 fertilized eggs. Healthy looking injected embryos will be transferred into a minimum of 4 pseudo females and their pregnancy will be monitored Two weeks after birth of potential transgenic pups, the researcher will be notified of the number of pups. MAPS will wean the pups at 21 days old and take ear notches to give to the researcher for genotyping.