The Genome Modification Facility (GMF) provides transgenic, gene targeting, and other services to investigators of Harvard University and its affiliated institutions, as well as to investigators within the US and abroad. The GMF performs microinjections of DNA into fertilized embryos to generate transgenic mice, DNA transfection into ES cells for the creation of recombinant ES cell clones, injection of gene-targeted ES cells into host blastocysts to generate gene knock-out or knock-in mice, teratoma formation studies, and other related ES cell-based services. Other services include cryopreservation of mouse sperm and embryos, in vitro fertilization, recovery of cryopreserved mouse sperm and embryos, rederivation of pathogen free mouse lines, and derivation ES cell lines from wild type and mutant mice with a variety of genetic backgrounds. Our staff provides general consultations on experimental designs and vectors for gene modification-related projects, DNA preparation, recombinant ES clones, mouse genotyping, colony breeding and husbandry. We can also customize services as requested to support development of animal models of human diseases. To contact us, please send an email to GMFmail@fas.harvard.edu.