Assisted oocyte activation significantly increases fertilization and pregnancy outcome in patients with low and total failed fertilization after intracytoplasmic sperm injection: a 17-year retrospective study.

Objective: To investigate the extent to which assisted oocyte activation (AOA) improves clinical outcomes in patients diagnosed with oocyte activation deficiencies (OADs).

Design: Retrospective cohort study comparing AOA cycles and previous intracytoplasmic sperm injection (ICSI) cycles in couples experiencing low or total failed fertilization after ICSI. Importantly, the sperm-related oocyte-activating capacity was examined in all patients before AOA with the use of the mouse oocyte activation test (MOAT).

Assessment of the calcium releasing machinery in oocytes that failed to fertilize after conventional ICSI and assisted oocyte activation.

Research Question: Can oocyte-related activation deficiencies be evaluated in oocytes that failed to fertilize after intracytoplasmic sperm injection (ICSI) combined with assisted oocyte activation (AOA)?

Design: Evaluation of the spindle-chromosome complexes and intracellular distribution of inositol trisphosphate type 1 receptors (IP3R1) in in-vitro matured (IVM) and failed-to-fertilize oocytes from patients undergoing AOA. Assessment of the oocyte-related Ca releasing capacity in response to Ca ionophores and sperm microinjection in oocytes that failed to fertilize after ICSI or ICSI-AOA.

Results: IVM oocytes from patients undergoing conventional ICSI (control) and ICSI-AOA (study group) revealed a similar normalcy of spindle-chromosome complexes and distribution patterns of IP3R1.

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

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.

Culture conditions affect Ca release in artificially activated mouse and human oocytes.

Inconsistent fertilisation and pregnancy rates have been reported by different laboratories after application of ionomycin as a clinical method of assisted oocyte activation (AOA) to overcome fertilisation failure. Using both mouse and human oocytes, in the present study we investigated the effects of ionomycin and Ca2+ concentrations on the pattern of Ca2+ release and embryonic developmental potential. In the mouse, application of 5μM ionomycin in potassium simplex optimisation medium (KSOM) or 10µM ionomycin in Ca2+-free KSOM significantly reduced the Ca2+ flux and resulted in failure of blastocyst formation compared with 10μM ionomycin in KSOM.

Single Ca transients vs oscillatory Ca signaling for assisted oocyte activation: limitations and benefits.

Oocyte activation is a calcium (Ca)-dependent process that has been investigated in depth, in particular, regarding its impact on assisted reproduction technology (ART). Following a standard model of signal transduction, Ca drives the meiotic progression upon fertilization in all species studied to date. However, Ca changes during oocyte activation are species specific, and they can be classified in two modalities based on the pattern defined by the Ca signature: a single Ca transient (e.

PLCζ is the physiological trigger of the Ca oscillations that induce embryogenesis in mammals but conception can occur in its absence.

Activation of the egg by the sperm is the first, vital stage of embryogenesis. The sperm protein PLCζ has been proposed as the physiological agent that triggers the Ca oscillations that normally initiate embryogenesis. Consistent with this, recombinant PLCζ induces Ca oscillations in eggs and debilitating mutations in the gene are associated with infertility in men.

Effect of two assisted oocyte activation protocols used to overcome fertilization failure on the activation potential and calcium releasing pattern.

Objective: To assess the effect of two assisted oocyte activation (AOA) protocols with the use of two calcium (Ca(2+)) ionophores, ionomycin and A23187 (calcimycin), on the intracellular Ca(2+) level in mouse and human oocytes and the fertilization rates.

Design: Comparison of two Ca(2+) ionophores, ionomycin and A23187, regarding their capacity to increase the intracellular Ca(2+) level and to support subsequent oocyte activation and development.

Setting: University hospital research laboratory.

Procaine Induces Cytokinesis in Horse Oocytes via a pH-Dependent Mechanism.

Coincubating equine gametes in the presence of procaine has been reported to facilitate in vitro fertilization, with cleavage rates exceeding 60%. We report that while procaine does trigger sperm hyperactivation, it independently induces cleavage of equine oocytes. First, we found that procaine (1-5 mM) did not facilitate stallion sperm penetration of equine oocytes but instead induced sperm-independent oocyte cytokinesis in the absence of the second polar body extrusion.

PLCζ disruption with complete fertilization failure in normozoospermia.

Purpose: Intracytoplasmic sperm injection (ICSI) is widely used to achieve fertilization in the presence of severe male factor, resulting in high fertilization rates. Nevertheless, 1-3 % of couples experience complete fertilization failure after ICSI. When a male factor is identified, assisted oocyte activation (AOA) can help overcome fertilization failures.