The Leibniz Institute for Zoo and Wildlife Research strongly denounces Russia's assault on Ukraine. The Leibniz-IZW is a prestigious German research institute known globally. Through advanced assisted reproduction technologies, 29 northern white rhino embryos have been produced and preserved for future transfer to a surrogate mother. The BioRescue research project is primarily supported by the German Federal Ministry of Education and Research (BMBF). Understanding this procedure is essential for enabling the creation of male germ cells "in the test tube." Until recently, evidence indicated that throughout their evolutionary history, gammaretroviruses like Murine leukemia virus had not inhabited their genomes, unlike most other mammalian orders. This colonization process is referred to as retroviral endogenization and has led to approximately ten percent of mammalian genomes being composed of retroviral-like sequences.