1-cell embryo Holding pipette Needle DNA Transfer to Embryo Injection into oviduct of dono 1-cell embryo surrogate dam @@ 10%-20% of pups will be transgenic Figure 7. 1. Making transgenic mice by pronuclear microinjection. DNA is injected througl a fine glass needle into the large male pronucleus of a 1-cell embryo while it is held to a blunt-nosed pipette by suction. Either soon after injection or next day the embryos are introduced by surgery into the oviducts of surrogate dams. Up to 20% of the pups that are successfully delivered are expected to have integrated the transgene