Patients with a high proportion of immature and meiotically resistant oocytes experience defective nuclear oocyte maturation patterns and impaired pregnancy outcomes

Abstract

Patients presenting with abnormally high numbers of immature oocytes at retrieval are more likely to exhibit maturation resistant oocytes. However, the clinical relevance of such events remains unknown. We investigated nuclear maturation competence of immature oocytes from patients showing >40% of collected immature oocytes (Study group) and Controls, in which a normal number of mature oocytes (≥60%) was retrieved. Following in-vitro culture, oocytes were classified as maturation resistant or in-vitro matured (IVM). Treatment outcomes were evaluated in Study and Control groups based on presence of maturation resistant oocytes. Overall, similarly high spindle and chromosome abnormality rates were observed in maturation resistant oocytes from both Study and Control groups. IVM oocytes from the Study group revealed significantly higher percentages of misaligned chromosomes compared with Controls (P < 0.05). Remarkably, Study group patients with at least one maturation resistant oocyte showed significantly reduced cumulative pregnancy and live birth rates compared with Control group maturation resistant patients (P < 0.05). When further investigating the aetiology, a maturation resistant mouse model revealed defective Ca signalling of maturation resistant oocytes at germinal vesicular breakdown and parthenogenetic activation. In conclusion, appropriate treatment strategies, including clinical utilization of IVM oocytes from Study group patients, warrant further investigation.

In vitro maturation (IVM) of oocytes in patients with resistant ovary syndrome and in patients with repeated deficient oocyte maturation

“…We agree with assumption of other authors that these cases represent intrinsic oocyte problems not influenced by the follicular environment and in vitro maturation media cannot be designed to overcome intrinsic causes of maturation arrest [15]. Although mature oocytes can be obtained after extended in vitro culture of denuded GV oocytes in patients with a high proportion of immature and meiotically resistant oocytes after COS and hCG triggering, this so-called rescue IVM strategy should be considered with caution, as oocytes that reach metaphase II after rescue IVM have a significantly higher percentage of spindle abnormalities and misaligned chromosomes [30].…”

In vitro Activation of mouse oocytes through intracellular Ca2+ regulation

“…Nonetheless, this response may represent the amount of intracellular calcium in the ER as well as the channel activity which is responsible for regulating calcium entry into the cells. [ 40 ]…”

Oocyte Activation Failure: Physiological and Clinical Aspects

“…Evaluation of cytoplasmic maturity with immunocytochemical methods revealed that metaphase plate rearrangements are more frequent in oocytes showing immaturity [70]. Another study investigated abnormal maturation in patients with a high proportion of immature oocytes [71].…”