Structural and morphologic differences in human oocytes after in vitro maturation compared with standard in vitro...

Area of Science:

• Reproductive biology and assisted reproductive technologies (ART).
• Embryology and gamete quality assessment.

Background:

• In vitro maturation (IVM) offers an alternative to traditional in vitro fertilization (IVF) for oocyte maturation.
• Oocyte quality, assessed by size and texture, is crucial for successful fertilization and embryo development.
• Polycystic ovary syndrome (PCOS) is associated with oocyte quality and may influence outcomes in ART.

Purpose of the Study:

• To compare oocyte/zygote size and texture between IVM and traditional IVF.
• To investigate the impact of these morphological parameters on fertilization and blastocyst development rates.
• To evaluate differences in patients with and without PCOS undergoing different ART procedures.

Main Methods:

• A prospective case-control study involving 83 participants/cycles undergoing IVF with intracytoplasmic sperm injection (ICSI) or IVM.
• Participants were categorized into PCOS-ICSI, Control-ICSI, and PCOS-IVM groups.
• Oocyte/zygote size and ooplasm texture were analyzed using ImageJ and maZda software at five key developmental stages.

Main Results:

• PCOS-IVM oocytes were significantly larger at early stages (sperm injection, second polar body extrusion) compared to both PCOS-ICSI and Control-ICSI groups.
• PCOS-IVM oocytes also showed increased size at the pronuclei disappearance stage versus the Control-ICSI group.
• Significant differences in oocyte texture were observed in early developmental stages, particularly when comparing PCOS-IVM to Control-ICSI, but not at later stages.

Conclusions:

• Oocyte size and texture exhibit significant differences during the early stages of the first cell cycle between IVM and IVF treatments.
• These early morphological variations may be influenced by the maturation method and patient characteristics like PCOS.
• No significant differences in size or texture were found by the stage immediately before cytokinesis, suggesting normalization or loss of early distinctions.