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 stat us (prophase I [PI] versus metaphase II [MII]) and in vitro culture on the kinetics of maternal messenger ribonucleic acid (mRNA) in human o ocytes. Design: Molecular biology on excess oocytes obtained from our clinical IVF program. Interventions: The oocytes, classified as either PI or MII at collection, were used as such or cultured in vitro for a n additional 24 hours. The relative levels of c-mos and cyclin-B1 were measured using semiquantitative reverse transcriptase polymerase chai n reaction (RT-PCR). Results: The mean levels of c-mos and cyclin-B1 t ranscripts were indistinguishable between the PI, MII, PI oocytes matu red in vitro, PI oocytes failing to mature, and MII oocytes cultured f or additional 24 hours. The variability in the levels of these transcr ipts increased during the in vitro culture. Conclusions: The levels of c-mos and cyclin-B1 transcripts were not different in PI versus MII o ocytes, therefore, differences seen in the clinical outcome of PI and MII oocytes may be unrelated to levels of these gene products. C-mos a nd cyclin B1 mRNA were maintained in vitro, thus degradation of matern al RNA is not activated in excess during the 24-hour culture.