DIFFERENTIAL TRANSCRIPTION OF LAMININ SUBUNITS IN MOUSE OOCYTE, PREIMPLANTATION EMBRYO AND PARTHENOGENOTE

To study the regulation of laminin expression in preimplantation embry ogenesis and oogenesis of mouse embryo, the transcriptions of laminin subunits, A, B1, and B2, were examined by polymerase chain reaction co upled with reverse transcription, And the expression of laminin subuni ts of parthenogenesised embryo was compared with that of normally deve loped embryo to examine whether they are imprinted in maternal genome, The mRNA of laminin B1 subunit was detected from the germinal vesicle stage oocyte, however, laminin B2 and laminin A mRNAs could not be de tected in all stages of oogenesis, Maternal laminin B1 mRNA was degrad ed and embryonal transcripts of laminin B1 accumulation started at the two-cell stage, The laminin B2 mRNA was detected after the four-cell stage and laminin A mRNA was expressed at the blastocyst, Therefore, t he three genes of laminin subunits are asynchronously transcribed duri ng mouse embryogenesis and oocyte maturation, On the other hand, the p arthenogenetic embryo cultured to the blastocyst expressed all three s ubunits of laminin mRNAs as the normally developed embryo did, This in dicates that the laminin genes are not imprinted in the mouse maternal genome.