Messenger ribonucleic acid kinetics in human oocytes—effects of in vitro culture and nuclear maturational status *

Objective To study the effects of different nuclear maturational status (prophase I [PI] versus metaphase II [Mil]) and in vitro culture on the kinetics of maternal messenger ribonucleic acid (mRNA) in human oocytes. Design Molecular biology on excess oocytes obtained from our clinical IVF program. Interventions The oocytes, classified as either PI or Mil at collection, were used as such or cultured in vitro for an additional 24 hours. The relative levels of c-mos and cyclin-B1 were measured using semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). Results The mean levels of c-mos and cyclin-B1 transcripts were indistinguishable between the PI, Mil, PI oocytes matured in vitro, PI oocytes failing to mature, and Mil oocytes cultured for additional 24 hours. The variability in the levels of these transcripts increased during the in vitro culture. Conclusions The levels of c-mos and cyclin-B1 transcripts were not different in PI versus Mil oocytes, therefore, differences seen in the clinical outcome of PI and Mil oocytes may be unrelated to levels of these gene products. C-mos and cyclin B1 mRNA were maintained in vitro, thus degradation of maternal RNA is not activated in excess during the 24-hour culture.