CELL-PROLIFERATION IS REDUCED IN PARTHENOGENETIC MOUSE EMBRYOS AT THEBLASTOCYST STAGE - A QUANTITATIVE STUDY

Background: Parthenogenetic and androgenetic embryos fail to develop t o term, possibly because of genomic imprinting, an epigenetic alterati on of certain genes, depending on the parent of origin, The effect of this phenomenon has been studied mainly in mid-gestation embryos, with out morphological abnormalities detected during the preimplantation pe riod, Nevertheless, parthenogenetic mouse embryos never develop to the blastocyst stage in the same numbers as do fertilized ones, and up to 50% fail to implant, suggesting that genomic imprinting may be respon sible for this lack of viability. Methods: We have made a quantitative and morphometric analysis of the cell proliferation capacity at the e nd of the preimplantation period in parthenogenetic mice to study if s uch parameter is affected by the monoparental constitution of the embr yos. Results and conclusions: We have found that, apart from the diffe rent morphology and cell number induced by culture conditions, parthen ogenetic mouse blastocysts have a significantly smaller cell number th an do fertilized control embryos, Our interpretation of these results is that the monoparental constitution of these embryos may be responsi ble for the lack of some factor required to sustain cell proliferation after the morula stage. (C) 1997 Wiley-Liss, Inc.