Morphology and developmental potential of bovine parthenotes after spontaneous activation in vitro
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Spontaneous parthenogenetic activation of bovine oocytes in an in vitro maturation and fertilization system (IVM/IVF) is described. Altogether, 1403 follicular oocytes, collected by the aspiration method, were matured in vitro and then cultured without insemination in the same conditions as a group of inseminated oocytes. After 48-72 h of additional culture, 141 oocytes (10%) were found to be spontaneously activated. Morphological evaluation revealed that the number of blastomeres within parthenotes ranged from 2 to 16 cells, with a minority (15.7%) comprising of 9-16 blastomeres. According to a cytogenetic analysis, only 1.2% of the analysed parthenotes consisted of more than 9 cells. Parthenotes may not be distinguished from embryos produced in vitro and spontaneous parthenogenetic activation in an IVM/IVF system indicates suboptimal culture conditions. A group of non-inseminated oocytes should be included in each experiment to serve as a control. Spontaneously activated bovine parthenotes only occasionaly developed beyond the 8-blastomere stage in a common IVM/IVF system. The incidence of parthenotes interferes with the efficiency of in vitro embryo production but it is doubtful whether it lowers the pregnancy rate after transfer of IVF embryos.
Publication order reference
D.Lechniak, Department of Genetics and Animal Breeding, Agricultural University of Poznan, ul. Wolynska 33, 60-637 Poznan, Poland