▁development , ▁as ▁they ▁facil itate ▁target ▁validation ▁and ▁the ▁study ▁of ▁response , ▁resistance , ▁to x icity ▁and ▁ph arm ac od ynam ics . ▁ ▁History ▁In ▁ 1 9 7 4 ▁Be atrice ▁M int z ▁and ▁Rudolf ▁Ja en isch ▁created ▁the ▁first ▁gen et ically ▁modified ▁animal ▁by ▁inserting ▁a ▁DNA ▁virus ▁into ▁an ▁early - stage ▁mouse ▁emb ry o ▁and ▁showing ▁that ▁the ▁inserted ▁gen es ▁were ▁present ▁in ▁every ▁cell . ▁However , ▁the ▁m ice ▁did ▁not ▁pass ▁the ▁trans g ene ▁to ▁their ▁off spring , ▁and ▁the ▁impact ▁and ▁applic ability ▁of ▁this ▁experiment ▁were , ▁therefore , ▁limited . ▁In ▁ 1 9 8 1 ▁the ▁labor ator ies ▁of ▁Frank ▁Rud d le ▁from ▁Y ale ▁University , ▁Frank ▁Cost ant ini ▁and ▁Elizabeth ▁L acy ▁from ▁Oxford , ▁and ▁Ralph ▁L . ▁Br in ster ▁and ▁Richard ▁Pal m iter ▁in ▁collaboration ▁from ▁the ▁University ▁of ▁Pennsylvania ▁and ▁the ▁University ▁of ▁Washington ▁inject ed ▁pur ified ▁DNA ▁into ▁a ▁single - cell ▁mouse ▁emb ry o ▁util izing ▁techniques ▁developed ▁by ▁Br in ster ▁in ▁the ▁ 1 9 6 0 s ▁and ▁ 1 9 7 0 s , ▁showing ▁transmission ▁of ▁the ▁gen etic ▁material ▁to ▁subsequent ▁gener ations ▁for ▁the ▁first ▁time . ▁During ▁the ▁early ▁eight ies , ▁Pal m iter ▁and ▁Br in ster ▁developed ▁and ▁led ▁the ▁field ▁of ▁trans gen esis , ▁ref ining ▁methods ▁of ▁ger ml ine ▁modification ▁and