EN
Two procedures for mass production of embryos for use in cattle breeding schemes are now available, namely multiole ovulation + embryo transfer and more recently in vitro embryo production. Hormonal treatment for multiple ovulation, nonsurgical embryo collection and embryo transfer are widespread techniques to obtain more offspring from genetically superior cattle (MOET programme).However, the costs can be considerable and the yield of embryos is highly variable.Research during the past decade has been focused on embryo production in vitro with oocytes from slaughterhouse ovaries and has tremendously succeed.Presently ultrasound guided technique for oocyte collection in living animals has been developed.However, both discussed procedures allow to use only a tiny part of high follicular capital of ovary.Bovine ovary contains many thousands of primordial follicles, but the vast majority become atretic during growth and maturation.Recently is developed a technique for in vitro growth of prenatal follicles rescuing them against atresia.It would offer a significant means for the propagation of valuable animal stocks and would be an addition to the methods already available for use in embryo production in vitro, since it would supply a large and uniform population of oocytes from genetically superior animals.