Modernization of the stages of technology in vitro maturation of donor oocytes in Bos taurus
Extracorporeal maturation of donors oocytes is the basic method in innovative cellular reproductive technologies (embryo production in vitro, cloning, transgenesis). Assessment of oocyte quality and improving media for maturation are the important tasks of embryo technology. The developmental competence of oocytes in different functional status (growing oocytes and oocytes that have finished growth phase in vivo) were analyzed on the base of comparative evaluation of morphology cumulus and chromatin status of oocytes (meiosis stages and level of degeneration).BCB-diagnostics based on the difference in color of ooplasm after the treatment by the vital dye brilliant cresyl blue was used to determine the functional status of the oocyte. The dynamics of the transformation of chromatin during meiotic maturation of oocytes were evaluated. The findings suggest the possibility of oocytes that have not finished growth phase in vivo can complete nuclear maturation in vitro with the prolongation of culture time. There were no significant differences in the proportion of degenerated oocytes during culture period up to 30 hours in all groups of experiment. System for in vitro maturation of bovine oocytes had evaluated by the BCB like growing oocyte is offered. Use of this system has increased embryo production up to 38%. The effect is achieved by addition into the medium maturation of 50 ng/ml prolactin, by addition the medium after 15 hours from start of culture 10 IU/ml of human chorionic gonadotropin and prolonged time of incubation up to 30 hours.