The cytogenetic constitution of embryos derived from immature (metaphase I) oocytes obtained after ovarian hyperstimulation

Commercially available enhanced in vitro maturation medium does not improve maturation of germinal vesicle and metaphase I oocytes in standard in vitro fertilization cases

“…Regardless of its efficiency in maturing GV oocytes in vitro, however, its ability to ultimately support normal fertilization remains unclear (13). Our results showed a maturation efficiency comparable to past studies comparing the Medicult IVM media to other IVM media .…”

Extended in vitro maturation of immature oocytes from stimulated cycles: an analysis of fertilization potential, embryo development, and reproductive outcomes

“…The slower cleavage rates often observed in IVM embryos have been potentially attributed to defective cytoplasmic maturation, either secondary to a loss of appropriate cytoplasmic proteins or due to a loss of synchrony between nuclear and cytoplasmic maturation, as evidenced by deficiencies in microtubule dynamics and chromatin phosphorylation in IVM oocytes [10,27]. Greater deficiencies in cleavage and genetic competency have been associated with duration of in vitro maturation, with extended duration in culture shown to be associated with spindle vulnerability; the metaphase spindle in aged oocytes no longer is observed on the periphery, but rather moves to the center of the oocyte [31,32]. Indeed, embryos originating from aged oocytes display a higher likelihood of abnormal cytoskeletal organization [33].…”

“…Immature GV oocytes matured in vitro exhibit a large number of genes expressed at more than a 2-fold higher level than in IVO-MII sibling oocytes, attributed to dysregulation of gene transcription and incorrect temporal utilization of transcripts [34]. Studies have thus demonstrated that IVM oocytes exhibit a higher proportion of complex chromosomal abnormalities as compared with IVO-MII oocytes, consisting of mosaic, nullisomic, and monosomic disruptions of normal chromosomal complements on fluorescent in-situ hybridization analysis of embryos in vitro matured for 24 h [10,32,35]. Such observations may account for the poorer reproductive potential for oocytes that have been in vitro matured in the present study, and provide strong evidence to favor embryos arising from in vivo matured oocytes over in vitro matured siblings when making selections for transfer.…”

The effect of human cumulus cells on the maturation and developmental potential of immature oocytes in ICSI cycles

“…In vitro maturation followed by fertilization opens a new avenue to make full use of the immature oocytes derived from controlled ovarian stimulation cycles. Several studies [1,6,9,12,17,27,32,34,35,41] have reported how to use the immature oocytes; however, the detailed influence of CCs on the developmental potential of human immature oocytes has not been extensively examined. In this study, our results indicated that, although there was no significant difference in the proportion of oocytes that reached metaphase II with the presence or absence of cumulus cells, it was noteworthy that an improvement in developmental potential was observed in the immature oocytes with CCs.…”

“…It has been reported that these in vitro matured oocytes lead to lower fertilization rates [1,9,34], abnormal embryonic development [1,4,34], and lower implantation rates [9] compared to oocytes that maturate in vivo. In these studies, the removal of cumulus cells from oocytes was performed after their retrieval before in vitro culture [1,6,9,27,32,34,35,41]. Some authors [16,17] also reported the developmental potential of immature oocytes that were not denuded of their cumulus cells (CCs) on the day of retrieval.…”