Use of a variable electrical pulsing sequence in rabbit oocyte activation

Area of Science:

• Reproductive Biology
• Developmental Biology
• Assisted Reproductive Technologies

Background:

• Oocyte activation is crucial for fertilization and embryonic development.
• Electrical stimulation is a common method for inducing oocyte activation in assisted reproduction.
• Variations in oocyte quality, such as first polar body morphology, may influence activation efficiency.

Purpose of the Study:

• To compare the electrical activation sensitivity of oocytes with whole first polar bodies (w-PB 1) and fragmented first polar bodies (f-PB 1).
• To assess the developmental potential of haploid embryos derived from both w-PB 1 and f-PB 1 oocytes.
• To determine the suitability of f-PB 1 oocytes as precursors for haploid embryo production.

Main Methods:

• Two groups of oocytes (w-PB 1 and f-PB 1) of similar post-ovulatory age were subjected to electrical stimulation for activation.
• The number of electrical pulses required for activation (extrusion of the second polar body) was recorded.
• Haploid activation rates and subsequent embryo development (8-cell, 16-cell, morula stages) were evaluated over 32 hours of culture.

Main Results:

• f-PB 1 oocytes required significantly fewer electrical pulses (2.9 ± 0.1) for activation compared to w-PB 1 oocytes (3.6 ± 0.2).
• Haploid activation rates were comparable between the two groups (68% for w-PB 1, 70% for f-PB 1).
• Oocyte type did not significantly impact the developmental ability of haploid embryos up to the morula stage.

Conclusions:

• Fragmented first polar body oocytes exhibit increased sensitivity to electrical activation.
• f-PB 1 oocytes are viable candidates for generating haploid embryos, supporting development to the morula stage.
• These findings suggest that f-PB 1 oocytes can be utilized in protocols aiming for haploid embryo production.