The key research areas of the Department are: in vitro production of embryos, embryo cryopreservation, animal transgenesis, cloning, cytometric semen sexing and evaluation. Research has been focused on the in vitro production of animal embryos, including the development of complex methods for oocyte maturation, fertilization and embryo culture. Moreover, experiments on long-term culturing of late preantral and early antral bovine ovarian follicles have been developed. Studies on the cloning of genetically modified pigs with "humanized" immunological systems have been undertaken. A cloned goat was produced from oocytes reconstructed with adult dermal fibroblast cells. The novel technique of rabbit chimeric cloning for the production of transgenic animals was applied; additionally, the recipient-donor-cell relationship in the preimplantation developmental competences of feline nuclear transfer embryos has been studied. Regarding transgenic animal projects, gene constructs containing growth hormone genes connected to the mMt promoter were used. Modifications of milk composition gene constructs with tissue-specific promoters were performed. Moreover, pigs for xenotransplantation and animal models of human vascular diseases have been produced. Over the last 15 years, our flow cytometry research group has focused its work on new methods for sperm quality assessment and sex regulation. In the 1970s, our team initiated studies on embryo cryopreservation. As a result of vitrification experiments, the world's first rabbits and sheep produced via the transfer of vitrified embryos were born.